In this paper, we describe a stochastic approach for previewing large irregular volume datasets with small memory resources. It is well known that the memory bandwidth consumed by visibility sorting becomes the limiting factor when carrying out volume rendering of large irregular volume datasets. To solve this problem, previous techniques without visibility sorting ignored absorption and emission in their optical models. Our technique represents a given irregular volume dataset as a set of opaque, emissive particles whose size is sufficiently small with respect to the pixel size. We applied our proposed technique to a volume composed of about 1G tetrahedral cells to confirm its effectiveness.

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A piston impact against a water column which is filled in a convergent nozzle can produce a high-speed impulse water jet. We analyze the behavior of such water jets with velocity of 500 m/s class in the atmosphere and its impingement on rigid wall by CIP method. The computational results are compared with the jet photograph taken by colored Schlieren method and deformation of aluminum specimen with the jet impact. Then, collision and break up of the water jets as well as shock waves around the jet are well simulated. As for the impingement of the water jet on a solid wall, it is shown that the aluminum crater is made mainly with water hammer pressure due to the jet impact. The computational result gives an explanation for the experimental fact that the crater gets deeper as the specimen is put far from the nozzle.

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One of the most promising approaches to reduce NOx emissions is based on the adoption of lean premixed flames. It is needed to obtain the ideally homogeneity of the air/fuel mixture. This study is aiming to clarify factors that have influence on mixing process of gaseous fuel with air by analyzing the instantaneous concentration of non-reactive fields of mixed gaseous fuel by laser-induce fluorescence (LIF). We showed usefulness of the acetone-LIF instantaneous measurement method to visualize instantaneous mixture field of gaseous fuel and air in swirling flow field using a high power laser system. Instantaneous concentration distributions using LIF show that a peak concentration decreases and the location moves outward with increase of height from exit of the fuel nozzle by swirling flow. It is clarified that deviation of concentration fluctuation decreases and the peak location moves outward as the height increases. It is indicated that characteristics of instantaneous concentration distributions with parameters of air ratio and vane angle.

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