Numerical method for nonequilibrium condensation and coagulation in critical conditions

第一年，将预条件流分裂格式与非平衡凝结可压缩流求解器相结合，提出了低马赫数非平衡凝结流动的数值计算方法。第二年，将三次状态方程之一的Peng-Robinson状态方程应用于超临界流体的密度、电导率、粘度等热性能的精确评定。然后，通过计算表明，在临界条件下，低马赫数下的二氧化碳流动即使是非常缓慢的流动，也表现为密度变化主导的可压缩流动。第三年，引入了热性能数据库PROPATH，并将其应用于数值计算。彭-罗宾逊可能只对超临界条件下的二氧化碳是准确的。由于该数据库具有48种物质的热学性质，不仅包括二氧化碳，还包括水、H_2、CH_4、NH_3、He等超临界条件下的热学性质，因此可以用该数值方法结合PROPATH计算任意物质在超临界条件下的流动。本项目的研究成果已在Int.J.Heat and Mass Transfer, j . p. phys等主要期刊上发表。并在一些国际会议上发表论文，包括2007年在圣地亚哥举行的第五届ASME_JSME流体工程联合会议。

In first year, a numerical method for flows with nonqulilibrium condensation at low Mach number was developed by combining the preconditioned flux-splitting scheme and the compressible flow solver for nonquilibrium condensation.In second year, the Peng-Robinson equation of state which is one of the cubic equations of state is applied to the method for evaluating thermal properties, such as the density, the conductivity, and the viscosity of supercritical fluids accurately. Then, it was shown by the calculations that carbon-dioxide flows near critical conditions at very low Mach number behave as compressible flows dominated by density variation even though they are very slow flows.In third year, the thermal-property database, PROPATH, is additionally introduced and applied to the numerical method. The Peng-Robinson may be accurate only for carbon-dioxide in supercritical conditions. Since this database has thermal properties for 48 substances, such as not only carbon-dioxide, but also water, H_2,CH_4,NH_3, He and so on in supercritical conditions, flows of arbitrary substance in supercritical conditions could be calculated by the present numerical method coupled with PROPATH.Research activities in this project have been published in major journals, Int.J.Heat and Mass Transfer, J.Comp.Phys., and Int.J.Heat and Fluid Flows, and also they have been presented some international conferences including the 5th Joint ASME_JSME Fluids Engineering Conference at San Diago,2007.