MODELING OF IRREGULARLY INDENTED ROUGH SURFACE FOR NUMERICAL SIMULATIONS OF TURBULENT FLOWS AND HEAT TRANSFER.

用于湍流和传热数值模拟的不规则锯齿状粗糙表面建模。

基本信息

批准号：
15560155
负责人：
MIYAKE YUTAKA
金额：
$ 2.3万
依托单位：
FUKUI UNIVERSITY OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

In this research project, it is indented to invent a method which gives simplified rough surfaces as models of randomly indented rough ones. The simplification is indispensable for computer simulation of turbulent flows over the surfaces, since computer power both in memory size and speed is limited. Demands from industry to estimate accurately thermo-fluid behaviors such as drag and/or heat transfer of irregularly indented surfaces are increasing sharply today and this project is to meet the demands. Fundamental strategy of the modeling is firstly to pick up dominantly important peaks which are large in scale and tall in height, and then to substitute selected peak areas by certain roughness elements of canonical shape such as hemisphere, con, circular cylinder, etc.. The thermo-fluid behaviors of roughness elements of canonical shapes are calculated by simulation, separately in advance. The fluid force and heat of the elements which are estimated by knowing local flow and thermal con … More ditions are imposed as two-dimensional external perturbations to the flow field in problem. Thus, final goal is to simulate a flow with thermal field of complex wall condition by a plane surface.The task done in this project is accordingly as follows. Fluid forces and rate of heat transfer of simple roughness elements, particularly of a hemisphere, which are mounted on a plane surface, periodically in line or in a staggered arrangement have been calculated by numerical simulations, assuming laminar flow in low Reynolds number and turbulent flow in high Reynolds number, based on RANS model. It was confirmed that pressure drop in a circular pipe flow using obtained data reproduces experiments which are cited from literatures, with satisfactory accuracy. Second task conducted was to construct a scheme which picks up dominantly important peaks. For this purpose, wavelet multi-resolution analysis(MRA) was introduced and extended to two-dimensional version. An adequately coarsened rough surface which removes small scale indentation, is obtained. From this simplified rough surface, a model rough surface composed of a group of roughness elements of canonical shape, hemispheres in many cases, is created. Dominantly important peaks are those having high peaks taller than a specified threshold value and one single continuous volume of tall peaks is replaced by a hemisphere of equal volume. The scheme for this conversion has been successfully established. It is required to validate the model surface, by comparing drag and heat transfer of the model rough surface and the original one, by numerical simulation. However, the computer resources available in this project did not allow us to complete this validation, though preliminary comparisons have been carried out. Less

在这个研究项目中，在Venet中，对表面上的动荡的计算机是必不可少的。如今，Iregular缩进的冲浪者的阻力和/或热量转移是急剧的，该项目是满足建模的基本策略等等。通过模拟，通过了解局部流动和估计的热量，可以通过模拟来计算典型形状的粗糙度元素的热流体行为。因此，最终目标是通过简单的粗糙度元素（尤其是半手机）模拟构图的热场，该元素安装在平面表面上，在线或在数字模拟的交错布置中。在跑步模型上，使用所获得的数据在圆形管流中的压力下降可重现文献的经验，并以令人满意表面Whist小规模的凹痕是从简化的粗糙表面元素中获得的相等的Hemisephie是通过数值模拟来验证模型粗糙表面和原始表面的热传递的。少了