Evaporation effect on calibration system for liquid micro flow sensors has been investigated since the evaporation effect becomes a significant error source of a weighing system as flow rate decreases. In the low-flow water calibration rig of NMIJ, the calibration factors were corrected by the evaporation rate, which was estimated without installation flow to the weighing tank. The evaporation rate from the weighing tank with and without water flow inside the weighing tank was evaluated experimentally, indicating that the effect of water flow inside the weighing tank on the evaporation rate was smaller than the evaporation rate. Based on the experimental results, future subjects of calibration apparatus for micro-flow or nano-flow ranges were discussed.

Fast response and high durability hydrogen sensor is required in the safety management of hydrogen refueling station. We had developed the catalytic combustion type hydrogen sensor in the shape of the miniature beads. We compared this fast response sensor with the conventional semiconductor type sensor in the performance of hydrogen leakage real-time monitoring. It was observed that the fast response sensor's output fluctuated with hydrogen concentration's short time change. It was confirmed that this fluctuation was useful for the early detection of the hydrogen leakage.

JAXA has constructed an experimental facility to pressurize and supply liquid hydrogen at a maximum pressure of 90 MPa to conduct experimental research on the injection of high pressure liquid hydrogen into the atmosphere. Liquid hydrogen has a property that its density greatly changes depending on pressure despite being a liquid phase. In addition, the high pressure hydrogen gas is in a supercritical state and has an intermediate property between a gas and a liquid. Therefore, it is a difficult question whether to treat the injection of high pressure liquid hydrogen as a gas phase phenomena or as a liquid phase phenomena. As a result of the experiment, it was found good to apply the liquid orifice equation to predict the discharge flow rate of high pressure liquid hydrogen.

At least once, air filling a piping from main hydrogen pipe line to an individual home end should be replaced with hydrogen gas to use the gas in the home. Special attention is required to complete the replacing operation safely, because air and supplied hydrogen may generate flammable/explosive gas mixture in the piping. The most probable method to fulfill the task is that, at first an inert gas is used to purge air from the piping, and then hydrogen will be supplied into the piping. It is easily understood that the amount of the inert gas consumed by this method is much to purge whole air, especially in long piping system. Hence, to achieve more economical efficiency, an alternative method was considered. In this method, previously injected nitrogen between air and hydrogen prevents them from mixing. The key point is that how much nitrogen is required to prevent the dangerous mixing and keep the condition in the piping safe. The authors investigated to find the minimum amount of nitrogen required to keep the replacing operation safe. The main objective of this study is to assess the effect of nitrogen and estimate a pipe length that the safety is maintained under various conditions by using computational fluid dynamic (CFD). The effects of the amount of injected nitrogen, hydrogen-supply conditions and the structure of piping system are discussed.

The human olfactories consists of two distinct kinds of spaces, i.e., the nasal cavity to breathe and the paranasal sinuses. Sinusitis is the inflammation of the mucous membranes of the paranasal sinus, which can be treated by endoscopic sinus surgery. The surgery uses an endoscope and a microdebrider (MD) which excises the tissues with a rotating hollow tip and suctions the removed tissues. When the MD is used at the vicinity of the eyeball, optic nerves may be damaged, and as a result, the patients may suffer from impaired eyesight due to the surgery. The important matter is controlling the tip of the MD during surgery. The purpose of this research is to devise a method for measuring the position of the tip with higher accuracy than the conventional method. In this study, we created a system which consists of piezoelectric vibration sensors, and measured the vibrations caused on the eyeballs during the surgery. We found two characteristic frequency components generated while the MD was rotating and sucking the morbid mucous membranes. By focusing on the higher frequency, the vibration measurement allows us to judge whether the MD is in a region where damage to the patient's eye can occur.

Water has significant influence on human body due to physiological carrier media. Therefore, an in vivo quantitative measurement of moisture content is necessary to clarify skin mechanics. In addition, rheological behavior of interstitial fluid in epidermal and dermal tissue, including blood micro-circulation, can vary skin mechanics in micro scale, i.e. viscoelasticity. Therefore, an in vivo quantitative measurement of capillary blood flow velocity is crucial to clarify their properties. In this paper, we propose 2C-OCM (2-Color Optical Coherence Moisuregraphy), which was composed of two-band light sources having different optical absorption properties of water respectively. These are capable of tomographically in vivo diagnosing the moisture content. Furthermore, OCDV (Optical Coherence Doppler Velocigraphy) algorithm can visualize the tomographic flow velocity of red blood cell in capillaries of human epidermal skin. In this experiment, 2C-OCM & OCDV were in vivo applied to human forearm skin. Consequently, it was concluded that 2C-OCM and OCDV can provide micro tomography of moisture content and capillary blood velocity inside skin tissue.

Rheological behavior of interstitial fluid in epidermal and dermal tissue, including blood micro-circulation, can vary skin mechanics in micro scale, i.e. visco-elasticity. Therefore, an in vivo quantitative measurement of capillary blood flow velocity is crucial to clarify their properties. The purpose of this study is to visualize the tomographic flow velocity of red blood cell in capillaries of human epidermal skin using Optical Coherence Doppler Velocigraphy, i.e. OCDV. This is constructed on a high frequency modulated low coherence interferometer, which is based on Hilbert transform and adjacent auto-correlation. In order to confirm the utility of OCDV, the tomographic distribution of capillary blood flow velocity was diagnosed with or without a vasodilator drug. As a result of in vivo applying OCDV to human cheek skins, this can reveal the vasodilation effect as well as the change of the blood flow velocity as an in vivo tomographic imaging.

Many of the elderly are predisposed to develop osteoarthritis (OA), although it is quite difficult to diagnose the early-grade OA even by latest imaging modalities. In this study, we have proposed Dynamic Mechanical Analyzing Optical Coherence Straingraphy, namely DMA-OCSA, which is a tomographically micro-visualizing method of visco-elastic properties estimated from continuous OCT images. This is based on the speckle tracking algorithm having high sensitivity and S/N under micrometer resolution, thus can provide temporal and spatial distribution of not only deformation velocity but also strain rate during a dynamic visco-elasticity test. This was experimentally applied to comparatively Osteoarthritic cartilage of animal models. Consequently, the sinusoidal time-varying strain rate was locally observed to have phase difference between the superficial tangential zone and middle zone, which could cause degradation of visco-elasticity.

Assessment of in vivo articular contact behavior at the wrist joint are important for understanding the biomechanical functions under physiological and pathological loading. The objective of this study was to evaluate in vivo articular contact behavior between the radius and scaphoid and between the radius and lunate using a two-dimensional to three-dimensional image matching technique. Two normal male subjects were enrolled in this study. Biplanar X-ray images were taken during dosal flexion/palmar flexion and ulnar/radial deviation of the wrist joint. The articular contact was estimated from the joint space distance smaller than the cartilage layer thickness measured using a MRI scanner. The distributions of estimated contact area and the contact locations varied markedly with wrist position. The present result would be able to provide a fundamental knowledge about the biomechanics of the wrist joint.

The interphalangeal (IP) joint of the thumb are formed by the articulation between the proximal phalanges head (PPH) and the distal phalanges base (DPB). The measurement of the contact behavior, i.e., distribution and magnitude of the joint contact area with motion is necessary to understand the effects of loading on articular cartilage. The purpose of this study is to determine the in vivo contact behavior of the IP joint of thumb using the MRI. Five normal right thumbs from 5 healthy subjects were examined. Subjects were scanned with their dominant hand in three positions. Contact area was determined by measuring the length of contact between the PPH and DPB in each slice, multiplying this length by slice thickness of 1-mm, and summing these values. We found that the average cartilage contact area attains a minimum value in the neutral position. We also found that the distal phalanx of thumb IP joint was caused internal rotation on the distal phalanx with flexion.

We have successfully fabricated an implantable drug delivery system (IDDS) on a microchip. This IDDS has a drug reservoir sealed by a thin membrane and two electrodes in the drug reservoir. One electrode is an active electrode generating electrically-induced bubbles, the other one is an opposed electrode. This device uses electrically-induced bubbles to release drug. Electrically-induced bubbles can be ejected with directional trajectory with high-speed enough to penetrate a thin membrane. We have successfully penetrated a membrane which store the drug by electrically-induced bubbles, and our device can release drug from a reservoir. This study can contribute to on-demand injection system for biomedical applications. One of the characteristics of our system is the speed of generating bubbles and penetrating a membrane for emergency purposes. In this paper, we present fabrication method of the device, and also the confirmed the performance of penetration of a thin polymer (PDMS) membrane and releasing drug. However, the penetration of a thin medicine was not sufficient and releasing drug is not as smoothly as we expected. Undergoing study is improving the efficiency of the system.

In order to predict fracture risks of osteoporosis, it is necessary to evaluate bone quality such as trabecular morphology in addition to bone density obtained from X-ray CT images of bone. Because it is difficult to obtain trabecular morphology from the clinical CT images of a patient due to the exposure dose of the X-ray, prediction of the trabecular morphology in micro scale corresponding to the bone density in macro scale is desired. As to obtain the trabecular morphology which corresponds to specific bone density has not been achieved using the existing remodeling simulation technique, a new method for the calculation of the trabecular morphology is essential. It is also necessary to assess relationship between the initial trabecular morphology and mechanical properties of the remodeled trabecular bone with its morphological change to examine the validity of the remodeling simulation technique. In this study, first, we performed bone remodeling simulation and evaluated apparent stiffness in macro scale for different initial trabecular morphologies. Second, we proposed a method to predict trabecular morphology corresponding to the target bone density based on the existing simulation technique. As results, stiffness of the trabecular morphology in macro-scale depended on the initial trabecular morphology. In addition, trabecular morphologies changed corresponding to the targeted bone density within the range from 0.2 to 0.7 of bone density. It means the potency of our proposed method.

Osteoarthritis is a disease with a high incidence rate among the elderly. This disease is caused by degradation of articular cartilage of knee. We have developed a device to diagnose the condition of articular cartilage of knee using ultrasonic. However, the reproducibility of the measurement result is low. In this study, we examined the contact state between the tip of ultrasonic probe and the skin to investigate the factor that reduces the reproducibility. Three skin specimens (artificial skin, RTV rubber and natural rubber) were used. The area of the contact part and the position of the center of gravity when the measurement is carried out were measured using a camera. From the image, the contact area was different from the actual delaychip size. Also, the position of the center of gravity in the contact area had variations (ΔX = 2.9 mm, ΔY = 2.1 mm) for each measurement. The skin specimens affected variations of center of gravity position. In addition, in the case of small contact area, the change in the signal intensity was small regardless of the kind of skin specimen and tilt angle. From this result, reproducibility can be improved by reducing the contact area between the tip of ultrasonic device and the skin.

Preservation method is studied to improve survival rate after preservation. In cryopreservation, cells are damaged by the growth of ice crystals. Therefore, using the phenomenon that freezing point of water becomes lower under high hydrostatic pressure, we investigated the method to preserve cells at subzero temperature by using hydrostatic pressure. As the experimental target, we chose eggs of medaka because it is easy to get and observe them. We observed the behavior of them under various temperature and pressure, and checked whether to hatch after experiment. As the result, we found that the path of pressuring and cooling had an effect to hatching rate. The hatching rate when pressuring after cooling is higher than pressuring after cooling. And longer the time of pressuring became, lower the hatching rate was. The lower pressuring rate improved the hatching rate. Utilizing hydrostatic pressure for preservation requires more long time experiments.

This paper describes development of regenerative medical system using microcapsules including gas by shock waves. The newly proposed system has two features. One is culture mode by pressure wave, and the other is rupture mode by interactions between shock waves and bubbles in microcapsules. Especially, the worked shock waves by using short-time laser with femto seconds will be generated in the water in this investigation. It was found that the optical system was established correctly by checking laser power. The control of power, duration and waves were discussed to improve the pressure waves in water. The result showed that (1) optical system was established by confirming maximum pressure at the focal point, (2) maximum pressure is 0.36MPa, and the pressure decays with distance from the focal point.

Bone strength is maintained by repeated bone resorption and formation. This metabolic activity is regulated by both biochemical factors, such as intercellular signaling, and mechanical factors, such as mechanosensing by osteocytes. We constructed a mathematical model of bone metabolism considering both biochemical and mechanical factors. In addition, we created a simulation model of cancellous bone based on X-ray micro CT images of a mouse femur. By using the constructed mathematical model and the cancellous bone model, we performed bone metabolism/remodeling simulation for cancellous bone under the same condition as a previous experiment using mice. The cancellous bone structure obtained by the remodeling simulation was quantitatively in agreement with the previous by reported experimental results. Through this comparison, we showed that the constructed simulator has a potential to quantitatively reproduce cancellous bone structure observed in mouse experiments.

During tissue morphogenesis, deformation of multi-cellular tissues proceeds by coordinated cellular activities, such as proliferation and constriction. For example, during optic-cup formation in an early eye development, neural retina, which is the distal region of the spherical optic vesicle, invaginates to form a two-walled cup-like structure. Previous study suggests that the deformation of retinal tissues is caused by mechanical effects of cellular proliferation and constriction. To understand the mechanism of the tissue morphogenesis, it is essential to understand how cellular activities mechanically influence the tissue deformation. However, the mechanical effects of cellular activities are still unknown because it is difficult to investigate the mechanical state in multi-cellular tissues through experimental approach. In this study, therefore, we performed computer simulation of optic-cup morphogenesis considering cell proliferation and constriction. Our simulation demonstrated the invagination process by incorporating non-uniform growth and relaxation of constriction, indicating that these two factors are necessary for the invagination.

In recent years, anti-aging, health and beauty, cosmetic and hair diseases attract attention. In particular, the hair has been very important in determining the human appearance. It is hoped that the formation mechanism in the root of hair will be clarified. However, it is difficult to observe the growth in root of hair and detailed mechanism has not yet been elucidated. Hair repeats growth and retraction, pause cycle (hair cycle) with a constant cycle. In the growth phase, hair is formed through processes of cell proliferation and differentiation (keratinization). During the regressive period, hair growth stops, and in the resting period it is said to be a period until hair comes out and new hair grows. It is believed that this hair cycle affects the elongation rate, thickness, strength and shape of hair. Therefore, in this study, we introduce a particle model as a new method to elucidate the process of unknown hair formation, and model the hair formation process accompanying the proliferation and differentiation of cells in the hair root part in the three-dimensional region. In addition, not only the growth period, but also the regression period and the resting period are introduced to realize the hair cycle using this model.

Cerebrovascular diseases are in the top group of the Japanese death causes in recent years, and among them, subarachnoid hemorrhage due to ruptured cerebral aneurysm occupies about 10% of them. Currently, the method for preventing subarachnoid hemorrhage is a surgery against an unruptured aneurysm, and in Japan, there are two types of surgeries: clipping and coilling. The method is selected according to the patient's symptom. Both surgeries have advantages and disadvantages. On the other hand, liquid filled type embolization using a catheter is also used overseas. This surgery can deal with an arbitrary shaped knob and has high embolism rate. However, it has a risk of the infusion solution flowing out of the knuckle, which is caused by the blood flow in the knob. Therefore, we investigate a high precision liquid injection simulation for confirmation of the safety of liquid filled embolization to a human body. On the simulation, we adopt MPS (Moving Particle Semi-implicit) method and generate a model that has a circular tube in a water tank by using particles, and perform the simulation by injecting liquid into the tube that imitates a catheter. However, the conventional MPS method is unstable on pressure vibration and surface tension calculation. Therefore, in this research, in order to improve the accuracy, two equations are used to solve the instability of pressure vibration and surface tension calculation. As the result of the simulation, we have confirmed that the liquid behavior in the simulation is similar to the real experiment.

Although it is important to understand the ideal techniques of coil embolization, it has not yet been well-known method yet. In this study, we perform finite element method-based structural analysis and computational fluid dynamics (CFD) to simulate coil embolization. we evaluate the hemodynamics and coil distribution in an aneurysm to identify the ideal methods of coil embolization. The results indicate that high packing density at neck region are critical to obtain effective velocity reduction.

Intracranial aneurysms (IAs) account for a large portion of cerebrovascular disorders and can be treated with flow-diverting (FD) stents. To aid the treating clinicians with determination of a favourable treatment plan, we adopted numerical simulation methods to the optimisation of FD treatment, including the design optimisation of FD stent wire structure, as well as the optimisation of FD stent treatment procedure. Our simulation results suggest that both stent design and stent deployment may drastically affect the FD treatment outcomes; numerical simulation prior to the real treatment may therefore assist the treating clinicians in predicting the treatment outcomes.

Flow-diverting (FD) stent is a commonly adopted devices for the minimally-invasive treatment of intracranial aneurysm (IA). With a FD stent properly deployed across the aneurysm orifice, it may discourage the flow from entering the aneurysm, thereby reducing the chance of aneurysm rupture. Using computational fluid dynamics (CFD) method, the aneurysmal haemodynamcis can be resolved to observe the flow-diversion efficacy and estimate the condition of aneurysm. Modelling the FD stent as a porous medium (PM) in the simulation, as an alternative to the original fully-resolved wire FD stent, is discovered to be an useful and flexible method to obtain the flow-diversion efficacy with improved simulation efficiency. However, current simulations with PM model FD stent tend to define the properties of the PM with consistent value, which fail to represent the different flow resistance result from the specific wire configurations in each stent of interest. Therefore, in this study, we aim to investigate a set of parameters for the calibrated PM stent model to represent a variety of commercially available FD stents and different treatment modes. The sensitivity in flow-diversion effects was observed with regard to the designing of PM model thickness and parameter settings of the PM model properties. Results indicate that the PM model thickness has negligible influence to the aneurysmal haemodynamics as long as the flow resistance are compensated to be identical, while the definition of PM properties, such as the permeability (k) and inertial resistance factor (C2), can induce flow-diversion effects with marked difference.

Holometabolous insects have imaginal discs, which are the pouch-like organs consists of monolayer epithelium, on their larval stages. Larvae unfold imaginal discs during pupation and form the exoskelton shape such as horns and limbs. In order to store the large exoskelton shape of adults in small body of larvae, imaginal discs are folded. Surprisingly, the structure of the imaginal disc is formed by folding the epithelial tissue from the planar shape autonomously. In developmental process of imaginal discs, epithelial sheet grows by cell proliferation and out-of-plane deformation is occurred. This deformation is affected not only by cell activities such as cell proliferation, but also by surrounding tissue. On the apical side of Drosophila leg disc, a kind of imaginal discs, squamous epithelium called peripodial membrane adheres to the disc. Due to this adhesion, out-of-plane deformation of growing leg disc is constrained. In this study, we investigate the mechanical effect of the deformation constraint by surrounding tissue using multicellular dynamics simulation based on 3D vertex model. Simulation results suggest that folding structure which has short wavelength is formed when constraining force from the surrounding tissue is acted on the disc. In addition, we examined the mechanism of folding structure formation from the viewpoint of minimizing mechanical energy. Our examination suggests that wavelength of folding structure is determined from the balance between the bending of the epithelial sheet and out-ofplane deformation of the surrounding tissue.

The Lucas-Kanade method, invented to represent an object’s displacement between successive images, was applied for tracking of a luminal surface of the left ventricle in echocardiographic images. To complement a variation in speckle patterns in the left ventricular wall caused by its deformation, a hill-climbing technique was used. Starting an image the resolution of which was reasonably lowered, we succeeded in tracking of the luminal surface of the left ventricle during cardiac cycle. Provided the velocity of the luminal surface and flow velocity data measured in a B-mode with Doppler echocardiography, hemodynamics in the long-axis plane of the left ventricle was well reconstructed. A series of flow velocity images well characterized general hemodynamic events such as formation of a vortex under the aortic valve in early diastole.

The Reynolds and Womersley numbers of the flow in human aorta are higher than those in the other arteries. This makes the flow more complex in the aorta, and accurate computational analysis more challenging. To address the computational challenges, we use a method consisting of two main components: Space-Time Variational Multiscale (ST-VMS) method and Isogeometric Discretization in the ST context (ST-IGA). The main objective in this research is to obtain reliable wall shear stress distribution with ST refinement study. We also assess the unsteady flow patterns in the aorta.

Heart valve flow analysis requires accurate representation of boundary layers near moving surfaces, even when the leaflets come into contact, and handling high geometric complexity. We address these challenges with a space-time (ST) method that integrates three ST methods in the framework of the ST-VMS method: the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and ST Isogeometric Analysis (ST-IGA). The ST-VMS, as a moving-mesh method, maintains high-resolution boundary layer representation near solid surfaces. The ST-TC enables moving-mesh computation with TC, such as contact between the leaflets, maintaining high-resolution representation near the leaflets. The SI connects the mesh sectors containing the leaflets, enabling a more effective mesh moving. Integrating the ST-SI and ST-TC enables handling contact location change and contact and sliding on the SI. Integrationg the ST-IGA with the ST-SI and ST-TC increases flow solution accuracy while keeping the element density in narrow spaces near contact areas at a reasonable level. The computations are for a realistic aortic-valve with prescribed leaflet motion and show the accurate solution near the leaflets.

Decreasing hemolysis and thrombogenesis is a major problem to realize the long-term use of blood pumps. In this study, we investigated the effect of discharge angle on pump properties of a monopivot centrifugal blood pump. Compared impellers had the same diameter, and they varied the discharge angle of the impeller which were 22.5°, 45°, 67.5°, and 90°. The axial thrust on the impeller, the estimated hemolysis index and the stagnation area around the pivot were calculated using computational fluid dynamics analysis. The pump driving condition was set at a flow rate of 4 L/min and a pressure head of 200 mmHg to simulate an extracorporeal circulatory condition. As a result, the rotational speed of the impeller was the lowest when the discharge angle was 90°. Although the axial thrust was the negative largest when the discharge angle was 22.5°, it was also kept negative for the other models, which indicated that all impellers will never lift off. The estimated hemolysis index was the lowest when the discharge angle was 22.5°, because high shear stress region around the outlet of the flow path was the smallest despite the rotational speed of the impeller was the highest. The stagnation area around the pivot was the smallest when the discharge angle was 22.5° because the flow rate through the washout holes was the largest due to the highest rotational speed of the impeller. Therefore, it was predicted that low discharge angle of the impeller improves both hemolytic and anti-thrombogenetic properties in the blood pump without considering other factors such as sliding of bearing and so on.

The effect of elasticity on the wall shear stress and the flow characteristic inside the cerebral aneurysm induced at the apex of bifurcation was experimentally investigated by the two-dimensional particle image velocimetry (2D-PIV) in vitro. The geometry of the aneurysm model used in the experiment was based on a patient-specific shape reconstructed from magnetic resonance images (MRI). Flow model simulates a patient-specific aneurysm induced at the apex of bifurcation in the middle cerebral artery. The elastic wall of the aneurysm model was constituted of transparent silicon rubber thickness 1mm. The maximum deformation rate of PIV measurement section was about 5~8%. These characteristics were examined for both elastic and rigid aneurysm models in pulsatile blood flow wave. The effect of wall elasticity on velocity of inlet flow was noticed in comparison with that of wall rigidity. We found that the wall deformation significantly reduced by several tens percent of the spatial and temporal averaged velocity of inlet flow in comparison with the non-deformable wall, and its maximum values in the elastic model is remarkably suppressed. Consequently, the elasticity of aneurysm wall significantly suppresses the magnitude, the spatial and temporal averaged velocity of inlet flow in comparison with the non-deformable wall.

TAVI (Transcatheter Aortic Valve Implanation) is one of treatments for Aortic Stenosis.Although TAVI has been established as a treatment less burdensome to patients, there is the fact that when PVL (Paravalver Leaks) occurs after surgery, life prognosis worsens. In the CFD simulation, it is shown that when a prosthetic valve smaller than the aortic inner diameter is placed, PVL is generated, which greatly affects mass flow loss and blood flow recirculation, causing thrombosis and aortic wall deformity . However, experiments using actual artificial valves have not yet been carried out satisfactorily. In this study, as a first step to investigate the cause of PVL, a prosthetic valve was placed in a simple cylinder tube, so that PVL does not occur, and analyze the flow around the prosthetic valve. We used the PIV system in the experiment. By this experiment, when the prosthetic valve is indwelled so as not to have a gap with the wall surface, it is understood that flow stagnation is occurring at the posterior part of the prosthetic valve, and it is considered that stagnation of this flow can cause thrombus formation. Through this experiment, We found the characteristics of the flow behind the prosthetic valve, and it became a foothold for clarification of PVL.

The relationship between the thrombus formation and internal structure in the left ventricle attracts attention of researchers. This study intends to clarify the effect of a simple papillary muscle model on the blood flow field in the left ventricle. A time-dependent computational model of a left ventricle was constructed from magnetic resonance images and blood flow analysis was performed. The left ventricle model deforms based on the length between mitral valve and apex and volume of the left ventricle measured with MR images. The blood flow fields and hemodynamic parameters were compared using the left ventricle models with and without the papillary muscle model. By the tracer particles for the flow and hemodynamic parameters, the stagnation of the blood flow was confirmed in the vicinity of the apex in the case of the model with papillary muscle model. Decreased time averaged wall shear stress, and increased oscillatory shear index and relative residence time for the model with papillary muscle also indicate the stagnation of the blood flow.

Bumblebees change their airfoils during a flapping cycle by rotating the hinges connecting the fore- and hindwings. Therefore, the instantaneous airfoil becomes an angled cross section like L-shape with a large camber. In this study, we experimentally and numerically investigated the aerodynamic characteristics of a flapping wing with angled cross sections. We measured unsteady aerodynamic force applied on a flapping wing with angled cross sections by using a scaled mechanical model in water tunnel. In addition, we conducted a numerical simulation of a flapping wing with angled cross section by using 3D Navier-Stokes code. The comparison between the experimental and numerical results shows a good agreement. As a result, the time-averaged lift for the angled flapping wings was inferior to that of the rigid flat plate. However, the instantaneous maximum lift for an appropriate angled cross section increases 32% larger than that of the flat plate at the center of the upstroke, when the wing has a positive camber.

We developed a magnetically driven flapping type micropump, which realized both heaving and pitching motion of a wing like insect's wing kinematics by using the elastic deformation of the wing structure. The pump performance of flow rate and pressure was measured and compared to the pump only with pitching motion. The experimental results indicate that the new flapping type micropump showed higher pump performance than the other because of its heaving oscillation. The maximum pump performace was obtained when the input frequency was close to the natural frequency considering the added-mass of fluid. In this case, the phase difference betwwen the input oscillation and output response was near 90 deg, which means the resonant phenomenon occurs at the input frequency.

Recently, many researchers have been regarding as important to realize high flight performance such as an insect's and bird's flights for the sake of precise and prompt survey of situation of disaster, development of the Mars airplane. In general, important features of the aerodynamics of biological flapping flyers result from large flapping wing movement and rotation, small size and low flight speed. In this study, various wings made of ABS resin with different taper configurations along with span and chord wise directions were manufactured by three-dimensional printer. The fluid force measurement by six-component load cell and PIV analysis are performed as the experimental method. The relation between the aerodynamic characteristics and fluid phenomena such as the layout of the leading-edge, trailing-edge and wing-tip vortices is considered.

This paper proposes a novel approach for fluid topology optimization using genetic algorithm. In this study, the enhancement of mixing in passive micromixers is considered. The efficient mixing is achieved by the grooves attached on the bottom of the microchannel and the optimal configuration of grooves is investigated. The grooves are represented based on the graph theory. The micromixers are analyzed by a Computational Fluid Dynamics (CFD) solver and the mixing performance is improved as the objective function by a genetic algorithm together with the Kriging model in order to reduce the computational cost. The mixing characteristics of the convex and the concave grooves are compared independently. In each case, GA finds several local optima since the objective function is a multi-modal function and each local optimum reveals a specific characteristic for efficient mixing in the micromixer. The results show a novel insight for design of a micromixer and fluid topology optimization using genetic algorithm.

Two-dimensional Navier-Stokes equation is solved in an analytical way by a perturbation method to investigate incompressible viscous flows between two intersecting permeable walls. The velocity components in cylindrical-polar coordinate system are expressed by means of a stream function, from which two unknown functions for the velocity components are appropriately defined. The perturbation method is applied to seek solutions of the functions. The functions obtained are both described by the forth order ordinary differential equations. In consequence, their function forms are correctly determined up to the first order approximation. The present solution contains Berman's solution for the flow between two permeable parallel plates, which is valid only in the zeroth order approximation. It reduces to the well-known two-dimensional Poiseuille flow between two parallel impermeable walls. It is also shown that the present solution includes Jeffery-Hamel's solution in the special case of impermeable walls for the same spatial configuration as the present one.

The authors have proposed a bypass type Nasal CPAP (BNCPAP) device of a vertical type of flow change. In the previous report, I investigated the influence of the outlet flow path of BNCPAP device and found the optimum shape. As a result of experiments with BNCPAP device with wide outlet channel attached to spontaneous breathing simulator (PT-2), CPAP pressure during exhalation became small during expiration. However, I did not know the influence of the bypass outlet channel. Therefore, in this report, the influence of the bypass flow path was experimentally investigated. From the experimental results, the role of the bypass flow path and its characteristics were clarified by the result of Sub pressure measurement. As a result, it was found that the CPAP pressure decreases below the MAP during exhalation and the possibility of decreasing respiratory work can be found. It was found that a bypass flow path having a sub-cavity is necessary.