The impeller geometry of the centrifugal blood pump affects the pressure flow characteristics, the rotational characteristic of the impeller, and the hemocompatibility of the pump. Therefore, several geometrical parameters of the impeller were summarized, and the effect of those parameters on those pump characteristics were considered for better designed blood pump. The impeller diameter, the vane geometry, the shroud geometry, and the washing way about the bearing or the seal were considered. Also, the impeller geometry was reconsidered about the design adaptation to the monopivot centrifugal blood pump.

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In a monopivot centrifugal blood pump, reducing stagnation areas especially around the bearing is very important. In this study, three models of impellers with different number of washout holes were proposed; the model with four flow paths and four washout holes, the model with six flow paths and six washout holes, the model with six flow paths and three washout holes. These impellers were made by 3D printing, and hydrodynamic performance, and impeller rotating position were compared among their assembled pumps. Next, their shear stress distribution inside the pump, which is closely related to the antithrombogenicity of the pump, was analyzed using computational fluid dynamics (CFD). As a result, the model with six flow paths and three washout holes was found to have high hydrodynamic performance, no lift-off problem, and high antithrombogenicity that had a small flow stagnation area.

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An ultracompact centrifugal pump has been developed as a blood pump of an implantable right ventricular assist device (RVAD). The centrifugal pump with hydrodynamically levitated impeller was designed at the working point of 5.0 L/min and 20 mmHg. The outer diameter of the impeller was 20 mm. The blade profile was optimized through numerical simulations of the flow field inside the pump primarily to reduce mechanical damages of blood cells during passing through the flow passages of the pump. The prototype was able to work at the design point at the rotational speed of 3000 rpm.

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A miniature axial flow blood pump that can be implanted at aortic root has been developed at Tokai University. In this study, a new impeller model for this axial flow pump was designed and the performance was numerically investigated. The pump has a rotor with three impeller blades. The span and axial length of the impeller blade are 1.15 mm and 13.9 mm, respectively. The inlet and outlet angles of each blade tip are 20.8° and 43.1°, respectively. The computational model of the pump placed in a tube with a diameter of 23 mm, which modeled an aortic root, was constructed and the blood flow was numerically calculated using a computational fluid dynamics (CFD) software. The pump performance predicted from the CFD results showed that the pump enables full support of left heart function at a rotational speed of 21000 rpm and that the partial support at 18000 rpm has potential to reduce the left ventricular load enough.

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Good clinical records seem to show expanded polytetrafluoroethylene (ePTFE) valve conduit may be a good choice for treating right ventricular outflow tract (RVOT) reconstruction in congenital heart defects. Bulging sinus of the ePTFE valve seem to have favorable effect on hemodynamic performance, however, fluid mechanical research proving this effect has been limited. This a part of the continuing effort to study the effect of the bulging sinus size of the ePTFE valve on the valve opening area and flow phenomenon inside the conduit. This time, model of live-sized ePTFE valve is utilized. Three valve conduit models with different bulging sinus sizes were used. Straight model, 80% reduced model, 25% reduced model, and normal model, were prepared. Effect of the bulging sinus size on a flow field inside the valve conduit was analyzed using Dynamic PIV system running at 1000 frames/s and valve opening areas were directly recorded using high speed digital camera running at 240 frames/s. Comparison of flow field results showed that the flow field of valve conduits with large Bulging sinus generates strong vortex inside the sinus. Valve opens wider as size of bulging sinus increases. Direct observation of the opening area of the valve showed that wider opening area was observed with larger bulging sinus models. Existence of strong vortex inside sinus seems to play important roll on valve open and close mechanism.

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We aimed to develop a calcified aortic valve model for the evaluation of paravalvular leak of a transcatheter aortic valve. We fabricated a calcified aortic valve model using silicone based on a CT image of the pre-operation of the patient who received treatment with a transcatheter aortic valve. In addition, we fabricated a thoracic aorta model and an abdominal aorta model because these three dimensional morphology would affect the insertion procedure of the transcatheter valve. These models were installed into a chamber, and the other space of the models were filled with a glycerol solution with the refractive index and viscosity of 1.410±0.002 and 5.96 mPa・s respectively, in order to adjust the expansion rate of the valve annulus and to measure the expansion range by a lazer system in pulsatile flow and pressure environments. Using the test system, the maximum and minimum cross-sectional area of the valve annulus in systole and diastole in the pulsatile flow circuit could be adjusted to these in the referenced patients' data. The pulsatile flow system with patient specific aortic valve, thoracic aorta and abdominal aorta model would be useful to quantify the paravalvular leak performance of the transcatheter aortic valve.

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In vitro antithrombogenic testing is a useful evaluation method for centrifugal blood pumps. We have been making clear a quantitative thrombosis model due to shear rate at between 0 and 2,880 s^<-1> for 3 hours and ACT between 200 and 1,000 s using a double-cylinder type rheometer, and apply to experimental conditions of the in vitro antithrombogenic testing. We focused on the blood coagulation reaction velocity of the coagulation factors under shear field. Porcine blood was used. After sheared, the plasma was obtained, prothrombin time (PT) and activated partial thromboplastin time (APTT) and the reaction velocity for the blood coagulation factors of II, V, VII, VIII, IX, X, XI and XII were measured using human diagnostic reagents by spectrophometry. As results, APTT was prolonged while PT was shortened. The intrinsic system was promoted while the extrinsic system was inhibited in vitro under shear field at 2,880 s^<-1> up to 3 hours, after measured reaction velocity of blood coagulation factors.

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Thrombus formations in medical devices are unsolved issue. If a reliable in vitro real-time visualization method is established, it will contribute the development and improvement of anti-thrombogenic medical devices. The aim of this study is to develop a real-time thrombus visualization system with an optical coherence tomography (OCT) and to reveal an influence of local blood flow on thrombus growth. We focus on the inlet and outlet part of connecters. The circuit was consisted of a roller pump, a reservoir, and resistance. The circuit volume was 50 ml. The blood flow rate and pressure were regulated to 100 ml/min and 70 mmHg. To visualize cross-sectional imaging of thrombus, we used a SS-OCT system with center wave-length of 1330 nm. OCT images were obtained every 10 minutes for 50 minutes. Test were performed 6 times. A fresh porcine whole blood with activated clotting time of approximately 200 sec was circulated. Thrombus-formed area increased with time at the outlet part of the connecter, however, the thrombus-formed area didn't increase at the inlet part. The part where thrombus-formed are increased was related to a flow-separation area. Flow-separation would be a cause to form such an increasingly thrombus. We revealed that the local blood flow is important not only for thrombus formation but also stability of thrombus-formed at the connecter.

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A clot of enzyme-activated milk in a low flow region was observed as a model of a venous thrombus. The milk was perfused in a micro channel with a custom made perfusion system A wall shear rate was controlled in the range of 10 to 22500 s^<-1>. A straight channel with a square cross section of which an edge length was 400 μm or 1200 μm was used. As a result of experiment, a milk clot formed along a channel wall. An amount of a clot increased with a decreasing wall shear rate when it was smaller than 10000 s^<-1>. On the other hand, an amount of a clot increased with a wall shear rate when it was greater than 10000 s^<-1>. A total mass of milk clot per wall surface area was greater in a wider channel.

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Hemolysis test of medical devices is a test to investigate the blood compatibility of the devices. This test has a potential problem that the test results depend on the initial quality of the blood used for the test. We have proposed a simple and rapid optical method to assess the fragility of the blood cells contained in the test blood. When the blood cells are exposed to low osmotic pressure, damaged cells collapse faster than normal cells. Therefore the fragility of cells can be estimated from the change speed of the optical properties of the cells. The proposed method has enabled fast screening. In this study, we focused on the very early stage of the osmotic hemolysis to provide a faster screening method. The new method enables the measurement of diameter change of the cells in swelling process with no calibration.

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This paper introduces the non-contact blood level measurement method for measuring in real time the reservoir volume from outside a venous reservoir using a pressure sensor. Results of the experiment, we have confirmed that the non-contact sensor to blood, the relationship of linearity in weight and blood level detection information of the reservoir and the measurement information is reproducible. This indicates that blood level can be estimated from a weight of the reservoir volume.

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In order to develop a non-invasive and non-contact vital sign monitoring system during sleep, we use a commercially-available depth sensor, Kinect for Windows v2, to obtain subject's respiratory data without any contact to his/her body. In the experiment, the depth sensor points at either chest or abdomen while a subject lies on a bed. The results are evaluated in terms of installation position of the depth sensor, and compared with the data from conventional contact-type respiration sensor. Experimental results reveal that the respiration frequency obtained from the depth sensor matches to the one from the contact-type respiration sensor when the subject lies on his/her back with one's head turned to upward. Moreover, the abdomen gives a larger signal than the chest. When the body is captured at the peripheral region of the sensing sight, however, the s/n ratio becomes lower. The higher the installation position is, the more artifact the system has.

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To meet the requirement for the new educational system in oral implantology at dental colleges that is expected to reduce the number of medical accidents in oral implant surgery, a new force sensing device for drilling the mandibular trabecular bone has been developed. The drilling force was calculated by stochastic multiscale finite element method based on the micro-CT images of cadavers. Not only the inter-individual difference but also the intra-individual difference, which means the variation of drilling force in the trabecular bone region, has been considered by the micro-CT image-based analyses. The multiscale method could analyze the anisotropic nature of the trabecular bone. Hence, the drilling in different angle results in different drilling force. The inter- and intra-individual differences and the consideration of anisotropy are essential in the education of bone quality. The calculated drilling force was implemented in the force sensing device that can control the drilling speed reflecting the input force. The developed system was used in the problem based learning (PBL) class at Tokyo Dental College. The result of the force sensing by students is reported, which supports the usefulness of the developed system.

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This research was conduced to generate the propulsion motion of lever-propelled wheelchair using forward dynamics simulation. This study used a neural model that consists of a rhythm generation system, a sensory feedback system, and a human-body model for the calculation of propulsion motion. The neural model parameters were optimized using a genetic algorithm. Results demonstrated that the proposed method can generate basic lever propulsion tasks such as pushing and pulling the lever.

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In recent years, people with swallowing disorders (dysphagia) have increased because of an aging population. More than 5,000 people die of asphyxiation each year after consuming solid foods in Japan. This study was conducted to develop an abnormal detection algorithm for a meal, especially the universal choking sign (hands crossed over the throat). In this study, magnetic position and orientation sensors were attached to three anatomical landmarks on the upper body of subjects and were used to measure human motion during a meal. Support vector machine was used for simulated choking sign detection Experimental results demonstrated that the proposed method detected simulated choking signs during a meal with accuracy of 93.7±4.1 %.

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A brain-computer interface has received a lot of attention for years, because this interface can be a useful tool for locked-in patients such as amyotrophic lateral sclerosis (ALS) patients. If the placement of the electroencephalogram (EEG) electrode becomes easier to attach, this interface will be more practical and become widely used among people including healthy individuals. In this research, we have focused on the forehead position called F_<p2>, and examined if the event-related potentials can be detected at this position. Comparing to the signal at the commonly-used occipital position O_z, the signal level at F_<p2> is evaluated with two proposed methods. Experimental results reveals that some subject has high accuracy at however, variance is quite large. Therefore, it is hard to draw a conclusion the signal level is better than the one at O_z. Using second evaluation method, one subject's accuracy at F_<p2> is nine times larger than others.

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Concentration has many factors, such as breadth, direction, and depth; however, the relationship of those factors and EEG has not been clarified. This research tries to reveal the relationship by; not using different kind of tasks to make different EEG characteristics, but also using same kind of tasks with different difficulty levels. The task we used is; a) show a certain size of matrix, b) show a blank matrix, and then c) let the subject write down the matrix numbers he/she remembers. All a), b), c) is shown only for a brief time. In this paper, we show that we can assume that differences in depth of concentration caused by different levels of difficulty in tasks, could change the EEG characteristics, in beta wave and theta wave band. We used OpenBCI to record EEG with disposal electrodes at F_z of International 10-20 system. We have not yet analyzed, or determined that this theta wave change between task state and rest state is Fm θ (Frontal-midline theta rhythm). Nor have we calculated if the change in EEG is whether significant or not. Further analysis is needed.

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Synesthesia is a hereditary condition in which a triggering stimulus evokes the automatic, involuntary, affect-laden, and conscious perception of physical or conceptual property that differs from that of the trigger. Synesthetes, who have synesthesia, can perceive more information than non-synesthetes. Imitating the mechanism of synesthesia, we are aiming to develop a system to integrate auditory and visual information. Such a system might be possible to provide richer world view to non-synesthetes. Moreover, it could enhance quality of life especially in hearing impaired. The system also could contribute to many fields including arts, learning, etc. At present, we are building a prototype system that allows users to perceive multiple sounds not only as auditory information but also as visual information like what synesthetes do. In the system, sound localization function, which is realized by the microphone array that consist of 4 microphones and purely based on Time Difference of Arrival, plays a great role. This paper describes the function and its accuracy.

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A pillow is an important item for sleep which effects on our quality of life. This study aims to establish a design method of a comfortable pillow shape for each individual from the shape of back head and neck (SBHN) in standing. This paper shows measurement tests of natural standing and lying position with a pillow. We made a measurement device of SBHN. Six subjects are measured their SBHN and head flexion angle in natural standing. In lying position, the subjects find their own best pillow from various height test pillows by sensory evaluation of comfortableness. We also measured the subjects' head flexion angle in each case of lying. There is a relationship between the SBHN depth in natural standing and the head flexion angle with the best pillow of each subject.

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It was reported that the body-weight supported treadmill training (BWSTT) is efficient as a rehabilitation for paraparesis and stroke patients in 1990s. BWSTT has been showed to be effective in gait reconstruction, but it has some problems; BWSTT is necessary 2 or more physical therapists and the stepping action makes therapists laborious work. Recently, Robot-Aided gait trainer has been developed to resolve these problems and in practical use is proceeding. Most of that consist of weight bearing device, treadmill, and orthosis that has actuators on hip joint and knee joint. Most of control method of actuators are tracking joint trajectories that instituted beforehand, so that it is decreased that opportunity that patients exert muscle power actively. Therefore it is being advocated that gait training by trajectory tracking might reduce efficient of rehabilitation. Also recently functional electrical stimulation (FES) have been studied. FES is treatment that reconstruct limb motion by stimulate peripheral muscles using electrical current from external to contract muscle, FES makes patients to contract his own muscle, therefore muscular hypertrophy is expected. However, in FES, generated muscle strength is not be steadied and it is difficult to keep posture using joint and ligament. In this study, we have developed a repetitive gait trainer for hemiplegic patients with a combination of actuator and FES. In addition, we report that actually performs a gait training healthy persons as subjects and confirms the operation and analysis of the device.

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This paper describes a gesture input interface using combination of head and eye movement. We develop a headphone device that can perform simultaneous measurement of the head and eye movement. The head motion is detected by an accelerometer and gyro sensor, and the eye movement, by a bio-potential amplifier as electro-oculogram (EOG). A major problem of such an interface is Midas touch problem, that some gesture motion becomes artifact and causes an unintended input. In order to reduce the influence of motion artifacts and solve the Midas touch problem, we perform experiments to evaluate daily motion such as "reading a book" in sitting on a chair. In addition, the motion, "gazing a target with head movement", is tested as a gesture movement. The present experimental results show that the eye movement in the yaw direction gives a large signal. It is caused by vestiburo ocular reflex (VOR) is frequently observed in the yaw direction during the gesture motion.

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This study was conducted to classify tongue motions of elderly people from surface electromyography (EMG) signals of the suprahyoid muscles detected at the underside of the jaw. The EMG signals were measured via 22 surface electrodes mounted onto a special flexible boomerang-shaped base. Root-mean-square features and cepstrum coefficients features of the EMG signals were extracted as features. An algorithm based on a support vector machine for pattern recognition was used to classify tongue motions. Results showed that six tongue motions were classifiable with accuracy of 86.1±9.6%.

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The tongue motor functions are usually preserved even in people with cervical spinal cord damage. Therefore, tongue motions might be used by people with severe movement paralysis to control home appliances such as electric wheelchairs and PCs. This study classified voluntary tongue motions using a tongue interface based on surface electromyography (EMG) signals of the suprahyoid muscles detected at the underside of the jaw. The classified motions were linked with electric wheelchair operation commands. Experimentally obtained results confirmed that voluntary tongue motions can control the electric wheelchair.

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Speech intelligibility varies according to the positions of speech organs, points of articulation, and control of air flow, as well as the manner of articulation. The purpose of this research is to develop a novel articulation training system that navigates the tongue tip to the appropriate points of articulation using vibration stimulus to the palate. For this study, thin-film piezoelectric elements were mounted on the palatal plate. They were used as a vibrator. The shape and driving frequency of piezoelectric elements were optimized based on subjective evaluations of vibration perception. Results demonstrated that the points of articulation can be perceived properly using the proposed method.

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Dental plaque is a primary factor of caries and periodontal disease. Manual tooth brushing is important to remove plaque. This research was conducted to develop a three-dimensional measuring system to evaluate tooth brushing skill objectively. A six degree-of-freedom magnetic motion tracking sensor was used to measure tooth brushing motion. Two three-dimensional force sensors were incorporated into the toothbrush's head and were used for tooth brushing force measurement. Experimental results showed that the brushing force vector and its application point can be quantified properly using the proposed system.

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Hyperthermia treatment is one of the physical treatments of cancer. It is based on the clinical fact that the cancer cells are weaker than normal tissue cells in the temperature range of 42-43 degrees Celsius. We have proposed the resonant cavity applicator for non-invasive hyperthermia treatments. In our previous study, we have already confirmed that the effectiveness of this applicator. However this applicator does not have the monitoring system to detect the location and size of a heated object and to measure the temperature distribution inside a human body. To overcome this problem, we proposed an ultrasound monitoring system using a diagnostic ultrasound imaging system. In this paper, we present a basic study of measuring temperature inside a human body using the diagnostic ultrasound imaging system. First, the method of measuring temperature was presented. Second, the experimental devices were presented. Third, the results of heating experiments and measured temperature from ultrasound images were presented. From these results, it was confirmed that the proposed monitoring system was useful for effective hyperthermia treatments.

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As a disease of bone "Osteoporosis" is a fatal threats in elder. Testing bone densities with "Duel Energy X-ray absorptiometry (DEXA)" in present provide expensive cost and harmful. We research the probability to create the noninvasive method by using knowledge of tissue optic. The potential of Near-Infrared (NIR) spectra are used to investigate the Absorption of the phantoms. The wavelength 800 and 1750 nm were used to consider the different between thickness and concentrations of bone for study the total intensity transmittance

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This paper describes a new heating method for treating osteoarthritis (OA) inside a knee using a resonant cavity applicator. OA is a common musculoskeletal disorder that causes pain, stiffness, swelling, and loss of function in a joint. As the disease progresses, the inflamed synovium invades and damages the cartilage and bone of the joint. In clinics, there are several treatments for OA, for example, surgical operation, thermal therapy, and chemotherapy. Physical methods, such as thermal therapy, with hot packs, paraffin baths, ultra-short waves, infrared lamps and microwave diathermy system are widely used for musculoskeletal disorders in the clinic. However, the skin penetration depth of these methods is less than approximately 20 mm. It is not easy to heat the affected part of the human knee. For an effective treatment of osteoarthritis, the deep seated joint cavity region in the human knee must be heated between approximately 36 and 38 ℃. In the previous study, a resonant cavity applicator for thermal therapy of OA was proposed. In this study, we proposed a new heating method using a resonant cavity applicator with adjustable electromagnetic shield. From the estimated results, it was found that the proposed heating method is able to heat the deep tissue with the leg in a bent position.

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The purpose of this study is to establish a 3D foot musculoskeletal model for designing functional footwear by using SIMM (ver7, Masculographics Inc.). In this report, eversion ankle sprain, damage of deltoid ligament, is focused to take into account. Foot joint movements and ligament loads are compared between two barefoot movements under no ankle support (no taping) and ankle support condition with stirrup taping technique (taping). As the results, the behaviors of Talocrual joint (TCJ) and Subtalar joint (STJ) angle during sidestep obtained from the experiment could be reproduced by the model in both no taping and taping conditions. Simulation results explained that Posterior Tibiotalar Ligament (PTL) and Tibilar Calcanear ligament (TCL) loads reduce with increase of elastic modulus of taping tape from 1.5 to 6.0kPa. Tranverse Tarsal joint (TTJ) under taping conditions got bigger internal and eversion angle than that under no taping condition. On the other hand, TCL which attaches TCJ and STJ were almost same load between no taping and taping conditions although TCJ and STJ angle depended on the constraint conditions. It is concluded that influence of foot constraint conditions on foot joints movements and the ligaments loads is quantitatively clarified with proposed foot model.

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The purpose of this study is to develop a three-dimensional deformation measuring device for measuring a sitting posture. Driver's seat position and posture affect the sitting comfort and fatigue while driving a car. Currently, ride comfort and fatigue have been evaluated with a sensory evaluation and body pressure sensor. However, since the seat surface is deformed when seated, it is necessary to measure the deformation. From measuring the deformation of the seat surface, it is found that the shape and angle of the surface is changed by the sitting posture. The measurement results, on occurrence conditions of the hip sliding suggests that it is necessary to study in consideration of deformation of the seat surface in a three dimensional space. Thus, three-dimensional deformation measuring device that we have developed are useful for the evaluation of the seat.

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The purpose of this study is the measurement of vital signs during sleep. Although there are many commercially available devices to measure vital signals, we present a system to detect heart beat and breathing rate during sleep using a sheet-shaped pressure sensor and signal processing, which allows for unsupervised and continuous measurement of vital signs. At this moment, smoothed signal root mean square autocorrelation for the heart beat and autocorrelation FFT peak positioning for the breathing rate are the methods used in the signal processing part. The experimental results from 3 subjects lying down in supine position are validated, and then compared to results measured by a respiration transducer and a pulse oximeter. For all subjects, the relative error of the breathing rate is less than 10%, and of the heart beat is less than 3%.

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CPAP (Continuous Positive Airway Pressure) for SAS patients is intended to continue to send the air of a constant pressure from the mouth and nose with a mask during sleep. Treatment in this way, and feel uncomfortable, such as stifling patients by positive pressure, it takes a long time to get used to the sleeping environment. It was considered possible to provide a comfortable sleep, than conventional breathing assistance device to SAS patients by applying the ventilator due to the pressure fluctuation is oscillatory flow instead of to conventional breathing assistance device. Experimental apparatus are composed by ventilation equipment, OSAS patient's upper airway obstruction model, and lung model with lung compliance. Half-life and pressure in the lung model were measured. As a result, in the upper airway it was a successful to be ventilated about the same half-life as released within airway. The higher frequency of the oscillatory flow, or tidal volume are applied, the shorter the ventilation time become. Lung model can be certainly ventilated by oscillatory flow, around in atmospheric pressure. Therefore, it will be more comfortable than CPAP.

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Functional disorder of the pulmonary emphysema has been believed due to dynamic compression of small airways. However, its direct evidences have never been shown. We hypnotized that overinflated lungs compressed the intra-mediastinal airway (IMA, intra-thoracic trachea, main bronchi, and right lobar bronchi) in emphysema at the beginning of forced expiration and would let IMA collapse due to fluid dynamical effect. We evaluated the morphological change of IMA during maximum forced expiration by 4D-CT, and investigated its relationship to the value of FEV_<1.0>. Five emphysema patients and a normal subject underwent 4D-CT by multi-detector row CT during maximum forced expiration over six seconds at supine posture. Voxel size was 0.7 mm x 0.7 mm x 1.0 mm with the range of 16 cm, and time interval was 0.5 sec. Volumes of intra-thoracic trachea and bilateral main bronchi are measured for each frame. The IMA of all emphysema patients were extremely narrowed just after the beginning of forced expiration and slightly recovered later. The membranous part of IMA was invaginated inside. There was no apparent shape change in the normal subject. The relative volume after two seconds was highly correlated to FEV_<1.0>. These 4D-CT images have revealed that low values of FEV_<1.0> in emphysema patients are caused by dynamic collapse of IMA. Pneumodynamics should be urgently reconstructed based on dynamic imaging.

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In recent years, High Intensity Focused Ultrasound (HIFU) has attracted attention as a treatment for cancers using focused ultrasound. In this treatment, ultrasound is irradiated from outside the body part to be focused on the target in the body, and kill cancerous tissue by thermal energy generated at the focal point. However, in order to carry out the treatment at a high temperature, there is a possibility that cauterizing also the normal tissue surrounding the tumor. Also, small HIFU devices have been developed, because large HIFU device expensive and large. But, so transducers are used to it is small, there is a disadvantage that its focal distance is short. In this study, we propose a control method of heating position with the vibration plate shape. Here, we propose the heating position control method of treatment according to the tumor location First, we presented a ring-shaped transducer model with the vibration plate for computer simulations. Second, we calculated pressure distributions from computer simulation using the Finite-Difference Time-Domain (FDTD) method. From these results, we found that the proposed control method was useful for HIFU.

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It is known that it is possible to enhance the axial dispersion in intermittent oscillatory flow through a pipe with circumferential grooves. In the present paper, The groove shape of the a pipe with circumferential grooves is focused. Gas transport experiment in intermittent oscillatory flow through a pipe having circumferential grooves both of square cross section and rectangular cross section. As a result, the effective diffusivity increases in the order of the aspect ratio of the groove of 0.6 with the groove depth of 6 [mm], The aspect ratio of 1.0 with the groove depth of 10 [mm]. The aspect ratio of 0.6 with the groove depth of 10 [mm].

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Airflow in a realistic nasal model was numerically simulated in order to investigate the transitional nature of flow. Computed tomography scans were used to reconstruct 3D realistic model of nasal airways. Direct numerical simulation of quiet restful inspiratory flow was performed using meshes with voxel pitches of 0.05 mm. This study investigates the effect of inflow velocity profile on transitional flow during steady nasal inspiration. Resultant velocity profiles and fluctuations were discussed in comparison between the naturally inflow profile and the simplified flat velocity profile at the nostril. As a result, simplified inflow profile is found to affect structure of the flow. The velocity fluctuations in flat velocity profile were smaller than those in the naturally inflow profile.

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