稀薄狀況下極音速熱流場數值分析軟體之發展計畫

Abstract

在這次計畫，我們希望朝三個方向進行，其簡介分別如下： 1､建構一具有NSPO RFP中要求具極超音速流之模擬能力的平行化直接模擬蒙地卡羅程式。 2､在本研究室的電腦叢集測試此平行化程式。（http://wwwdata.me.nctu.edu.tw/must） 3､建立一獨立的使用者介面前處理器用於協助此程式的前處理。 對於項目一 ，我們應建構一個可以模擬 3D 超音速稀薄流場的非結構網格的直接模擬蒙地卡羅程式。這程式的主要特徵為：動態領域切割､可變時步､平行化的可調適網格､各種不同自由度下的能量傳輸模型､空氣成分間的化學反應。在這計畫的尾端，直接模擬蒙地卡羅程式將加入共軛熱傳模型､流體及其表面的熱輻射､太空船表面的熱傳導的模擬能力以期可模擬航空器的熱負載。 對於項目二，發展完成的程式將在本研究室的電腦叢集上進行測試（20個節點， 單一處理器為一個節點）（詳見http://wwwdata.me.nctu.edu.tw/must）。 計畫模擬的流場包括超音速流體流經hollow cone flare 及 cone-cone（indented cone）並與其實驗數據進行比較。 在項目三 ，一獨立的可視化前處理器將被建構用於3D非結構性網格的處理。其主要特徵為：具有設定邊界條件､初始條件､材料特性及領域切割的能力。此外，不同計算與物理模組的可視化選擇的建構也將包含在此計畫內。

In this proposal, we intend to accomplish the research tasks in three directions, which are summarized as follows: 1. To develop a parallel direct simulation Monte Carlo (DSMC) code with simulation capabilities requested by the RFP of NSPO. 2. To test the completed code on the PC-cluster system at our laboratory (http://wwwdata.me.nctu.edu.tw/must). 3. To develop a stand-alone graph user interface for preprocessing tasks of running the developed parallel code. In the item 1, we shall develop a three-dimensional hypersonic rarefied flow solver using the direct simulation Monte Carlo (DSMC) method on unstructured tetrahedral mesh. Major features of this flow solver include parallel processing using dynamic domain decomposition, variable time-step scheme in combination with solution-based parallel adaptive mesh refinement, energy transfer models among various degrees of freedom and chemical-reaction treatment for air species. At the end of the project, conjugate heat-transfer module, considering the radiation between surface and flow, and conduction within the spacecraft surface, is coupled with the DSMC solver for simulating the heat load of the flying object. In the Item 2, the completed code will be tested using PC-cluster system (20-node, single processor per node) at our laboratory (http://wwwdata.me.nctu.edu.tw/must). Planned test cases include hypersonic flows past hollow cone flare and cone-cone (indented cone), which systematic experimental data has been reported extensively. In the Item 3, a stand-alone visual preprocessing will be developed to assist the preprocessing tasks for three-dimensional unstructured mesh. Main features of the visual preprocessor include settings of boundary conditions, initial conditions, material properties and initial domain decomposition. In addition, visual selection of various computational and physical modules developed in this project will be included in this preprocessor.