基礎資料
廢話不多說，首先羅列一些筆者參考的資料
openFOAM的官方網站為：https://openfoam.org/
東嶽流體網站：http://www.dyfluid.com/
本文使用的為openFOAM7版本，可以從網上下載下傳到提前預裝好的虛拟機，進而避免了安裝的麻煩。
openFOAM7安裝和虛拟機：http://www.dyfluid.com/docs/install.html
openFOAM7網頁使用者手冊：https://cfd.direct/openfoam/user-guide/
另外openFOAM還對應了一本英文的算法書《The Finite Volume Method in Computational Fluid Dynamics》，而且使用者手冊在CSDN可以找到中文翻譯版，其中一個版本主要為東嶽流體翻譯。
另外在b站也有很多線上的視訊資料，這裡不一一羅列。
combustion/chem檔案夾
我們主要關注燃燒，即如下路徑中的幾個算例以及其拓展
~/OpenFOAM/OpenFOAM-7/tutorials/combustion/
這個子產品中，包含如下部分：
[email protected]:~/OpenFOAM/OpenFOAM-7/tutorials/combustion$ ls
chemFoam fireFoam reactingFoam XiFoam
coldEngineFoam PDRFoam XiEngineFoam
目前筆者正在閱讀的是chemFoam,這裡主要計算的是純化學反應。
[email protected]:~/OpenFOAM/OpenFOAM-7/tutorials/combustion$ cd chemFoam/
[email protected]:~/OpenFOAM/OpenFOAM-7/tutorials/combustion/chemFoam$ ls
gri h2 ic8h18 ic8h18_TDAC nc7h16 README
代碼還給我們準備了
README
檔案，内容如下：
Stiff chemistry solver validation test cases
gri : GRI-Mech 3.0. CH4 combustion, 53 species, 325 reactions
h2 : H2 combustion, 10 species, 27 reactions
nc7h16 : n-Heptane combustion, 544 species, 2446 reactions
ic8h18 : iso-Octane combustion, 874 species, 3796 reactions
Results interpreted in 'validation' sub-directory, where OpenFOAM results
are compared against those predicted by CHEMKIN II.
Overall the best performing ODE solver is seulex followed closely by rodas23.
即目前幾個檔案夾分别對應幾個純化學反應，用來驗證剛性的化學反應求解器是否有效。并在
validation
中将目前結果與
CHEMKIN II
中的計算結果進行比較。結論是
seulex
和
rodas23
這兩個求解器性能較好。
h2算例的執行
我們參考OpenFOAM教程中的方法，首先将
h2
整個檔案夾複制到如下路徑：
[email protected]:~/OpenFOAM/dyfluid-7/run/h2/validation$ cd ~/OpenFOAM/OpenFOAM-7/tutorials/combustion/chemFoam/
[email protected]:~/OpenFOAM/OpenFOAM-7/tutorials/combustion/chemFoam$ cp -rf h2/ ~/OpenFOAM/dyfluid-7/run/
進入複制後的檔案夾中，運作方式有兩種，可以通過檔案夾中的
./Allrun
和
./Allclean
運作以及結果的删除，或者直接執行預設的指令
chemFoam
。注意兩者的差別，前者為編譯好的可執行檔案，後者為一個預設的指令。從執行結果來看，前者将本來應該輸出到終端的部分，儲存在了一個日志檔案
log.ChemFoam
中。
這裡給出一部分執行輸出：
[email protected]:~/OpenFOAM/dyfluid-7/run/h2$ chemFoam
/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 7
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
Build : 7-f1e51ce8d094
Exec : chemFoam
Date : Jun 08 2020
Time : 21:36:19
Host : "dyfluid"
PID : 4519
I/O : uncollated
Case : /home/dyfluid/OpenFOAM/dyfluid-7/run/h2
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time
Overriding DebugSwitches according to controlDict
SolverPerformance 0;
Constructing single cell mesh
Reading initial conditions.
Creating base fields for time 0
Reading thermophysical properties
Selecting thermodynamics package
{
type heRhoThermo;
mixture reactingMixture;
transport sutherland;
thermo janaf;
energy sensibleEnthalpy;
equationOfState perfectGas;
specie specie;
}
Selecting chemistryReader chemkinReader
Selecting chemistry solver
{
solver ode;
method standard;
}
StandardChemistryModel: Number of species = 10 and reactions = 27
Selecting ODE solver seulex
Reading/calculating face flux field phi
pressure will be held constant.
p = 202650 [Pa]
T = 1000 [K]
rho = 0.589632 [kg/m^3]
Starting time loop
deltaT = 1e-07
Time = 1e-07
Qdot = -824.966, T = 1000, p = 202650, H2 = 0.0144672
ExecutionTime = 0.01 s ClockTime = 0 s
deltaT = 1.9996e-07
Time = 2.9996e-07
Qdot = -789.321, T = 1000, p = 202650, H2 = 0.0144672
ExecutionTime = 0.01 s ClockTime = 0 s
deltaT = 3.9976e-07
Time = 6.9972e-07
Qdot = -717.117, T = 1000, p = 202650, H2 = 0.0144672
ExecutionTime = 0.01 s ClockTime = 0 s
deltaT = 7.9888e-07
Time = 1.4986e-06
Qdot = -575.829, T = 1000, p = 202650, H2 = 0.0144672
ExecutionTime = 0.01 s ClockTime = 0 s
deltaT = 1.59776e-06
Time = 3.09636e-06
...
Number of steps = 45
End
chemFoam的源代碼
我們希望通過閱讀單獨的算例，了解openFOAM整體程式的運作機制，而不是純粹機械的改參數跑程式。而所有的程式代碼，儲存在如下路徑：
[email protected]:~/OpenFOAM/OpenFOAM-7/applications
我們剛才使用的
chemFoam
在其中的如下檔案夾中：
[email protected]:~/OpenFOAM/OpenFOAM-7/applications/solvers/combustion/chemFoam
其中包括如下内容：
[email protected]:~/OpenFOAM/OpenFOAM-7/applications/solvers/combustion/chemFoam$ ls
chemFoam.C hEqn.H setDeltaT.H
createBaseFields.H Make solveChemistry.H
createControls.H output.H thermoTypeFunctions.H
createFieldRefs.H pEqn.H YEqn.H
createFields.H readControls.H
createSingleCellMesh.H readInitialConditions.H
好！本帖就到這裡，接下來會嘗試閱讀這裡面源檔案的内容。
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