@东岳 如果是像fluent中DPM里颗粒都是mass point的话就不存在这个问题了。

externalWallHeatFluxTemperature，将q设为0.

不过我用这个BC加恒定热流密度，后处理用wallheatflux计算，发现有个min/max区间，integral的值比应该注入的能量少0.3W（48.8W VS 48.5W），不知道这是否正常。

感谢大家分享！:xiexie: 论坛急需散金币机制。暂且欠每人1000金币！:w:

@东岳 好的我试试，谢李老师

This is the OpenFOAM language.
http://www.thevisualroom.com/24_openfoam_language/openfoam_language.html

What are features of C++?
What is explicit evaluation?
What is implicit evaluation?
What are the higher level data types?
What are fields?
What are the three types?
What are the five basic classes?
What are the three space-time classes?
What are the three field algebra classes?
What are the two discretisation classes?
What is a geometricField<Type>?
What is the objectRegistry?
What is the IOobject?
How is a dictionary object read?
How is volVectorField read from disk?
How is volScalarField constructed?
What are the read and write options?
How are objects represented in OpenFOAM?
How is matrix inversion done in fvm?
What are lists?
What are fields?
How is memory accessed?
How is IO Communication done?
How are derivatives of fields evaluated?
What are the functions for discretisation?
How can are equations translated into code?
How is the PISO algorithm programmed?
What are header files?
What is wmake?
1.1.1. What are features of C++?
Feature Meaning
typedefs Alias for a possibly complex type name
function Group of statements that perform a task
pointers Data type that holds addresses to refer to values in memory (e.g. for dynamic memory allocation)
data structures Data members grouped under one name (e.g. the nodes in a linked list)
classes Data members and function members grouped under one name
constructor Function member that initialises the instance of it’s class
destructor Function member that destroys the instance of it’s class
friends Allows a function or class access to private or protected members of a class
inheritance Allows a class to be created based on another class (so code can be reused)
virtual member functions Member function that will be redefined in a derived class
abstract class Class that contains at least one virtual function
template Family of classes (class template), functions (function template), variables (variable template) or alias of a family of types (alias template)
namespace Prevents name conflicts in large projects
1.1.2. What is explicit evaluation?
Evaluate spatial derivatives at the current timestep
Uses known values
1.1.3. What is implicit evaluation?
Evaluate spatial derivatives at future timestep
Uses unknown values - generates a matrix equation to be solved
1.1.4. What are the higher level data types?
Type Meaning
volScalarField
scalar, e.g. pressure
volVectorField
vector, e.g. velocity
volTensorField
tensor, e.g. Reynolds Stress
surfaceScalarField
surface scalar, e.g. flux
dimensionedScalar
constant, e.g. viscosity
1.1.5. What are fields?
Arrays of data stored at cell centres in the mesh

Include bouundary information

Three types
volScalarField
volVectorField
volTensorField
Values are stored in named dictionary files in named timestep directories e.g. case/0/p for pressure

1.1.6. What are the three types?
<Type> refers to:

scalar
vector
tensor
1.1.7. What are the five basic classes?
Class Meaning
fvPatchField
(and derived classes)

Boundary conditions
lduMatrix
fvMatrix
(and linear solvers)

Sparse matrices
1.1.8. What are the three space-time classes?
Class Meaning
polyMesh
Stands for polyhedral mesh

Most basic mesh class

Contains:
pointField
faceList
cellList
polyPatchList
fvMesh
Extends polyMesh contains:
Cell volumes (volScalarField)
Cell centres (volVectorField)
Face area vectors (surfaceVectorField)
Face centres (surfaceVectorField)
Face area magnitudes (surfaceScalarField)
Face motion centres (surfaceScalarField)
Time
Class to control time during OpenFOAM
Declared as variable runTime
Provides list of saved times runTime.times()
Timestep = deltaT()
Return current directory name = name()
Time increments = operator++() operator+=(scalar)
Write objects to disk = write()
Start time, end time = startTime(), endTime()
1.1.9. What are the three field algebra classes?
Class Meaning
Field<Type>
Array template class, e.g. Field<vector> = vectorField

Renamed using typedef as:
scalarField
vectorField
tensorField
symmTensorField
tensorThirdField
symmTensorThirdField
dimensionedField

geometricField<Type>
Combination of:
Field
GeometricBoundaryField
fvMesh
dimensionSet
Defines values at all locations in domain with aliases:
volField<Type>
surfaceField<Type>
pointField<Type>
1.1.10. What are the two discretisation classes?
Class Meaning
fvc
Stands for finite volume calculus
Explicit derivative evaluation
Input = known geometricField<Type>
Output = geometricField<Type> object
fvm
Stands for finite volume method
Implicit derivative evaluation
Input = unknown geometricField<Type>
Output = fvMatrix<Type> object, which can be inverted in the matrix equation Mx=y
1.1.11. What is a geometricField<Type>?
volField<Type>
surfaceField<Type>
pointField<Type>
1.1.12. What is the objectRegistry?
Object registry of entities (dictionaries, fields) which are to be read in or written out

1.1.13. What is the IOobject?
Defines I/O attributes of entities managed by the object registry.

1.1.14. How is a dictionary object read?
Code Meaning
Info << "Reading transportProperties" << endl;
Send message to screen
IOdictionary transportProperties
(
IOobject
(
"transportProperties",
runTime.constant(),
mesh,
IOobject::MUST_READ
IOobject::NO_WRITE
)
);
Read in at creation
dimensionedScalar nu
(
transportProperties.lookup("nu")
);
Lookup viscosity in dictionary
1.1.15. How is volVectorField read from disk?
Code Meaning
volVectorField U
(
IOobject
(
"U",
Times[i].name(),
runTime,
IOobject::MUST_READ
),
mesh
)
volVectorField read in from disk
Associated with runTime database
Must be read
1.1.16. How is volScalarField constructed?
Code Meaning
volVectorField magU
(
IOobject
(
"magU",
Times[i].name(),
runTime,
IOobject::NO_READ
IOobject::AUTO_WRITE
),
::mag(U)
);
magU.write();
construct mag(U) object of type volScalarField called magU
write it out
1.1.17. What are the read and write options?
Class Meaning
NO_READ
Object created
MUST_READ
READ_IF_PRESENT
Object asked to read
NO_WRITE
Object destroyed
AUTO_WRITE
Object asked to write
1.1.18. How are objects represented in OpenFOAM?
How to create an object that writes the magnitude of a velocity vector?

Class Meaning
#include "fvCFD.H"
int main(int argc, char argv[])
{

include "addTimeOptions.H" include "setRootCase.H" include "createTime.H"

instantList Times = runTime.times();

include "createMesh.H"

One block called main is needed
#include to store commonly used code
runTime is a variable of the OpenFOAM Time class - for timestepping through code
for(label i=0; i<runTime.size(); i++)
{
runTime.setTime(Times[i],i);
Info << "Time: " << runTime.value() << endl
volVectorField U
(
IOobject
(
"U",
Times[i].name(),
runTime,
IOobject::MUST READ
),
mesh
);
Loop over all possible times
Read in a volVectorField U
volScalarField magU
(
IOobject
(
"magU",
Times[i].name(),
runTime,
IOobject::NO READ,
IOobject::AUTO WRITE
),
::mag(U)
);
magU.write();
} return 0;}
Construct a volScalarField magU
Write out the velocity
1.1.19. How is matrix inversion done in fvm?
Each operator in fvm constructs particular entries in known M and y as a fvMatrix object
fvMatrix is a template class (actual classes are fvScalarMatrix etc)
fvMatrix handles storage via lduMatrix class
fvMatrix class also handles solution
1.1.20. What are lists?
Class Meaning
List<Type>
Array template class
Allows creation of a list of any object of a class e.g. List<vector>
PtrList<Type>
List of pointers
SLList<Type>
Non-intrusive singly-linked list
1.1.21. What are fields?
Class Meaning
Field<Type>
Array template class, e.g. Field<vector> = vectorField

Renamed as scalarField, vectorField, tensorField, symmTensorField,
tensorThirdField and symmTensorThirdField

1.1.22. How is memory accessed?
Arrays
Pointers
References
1.1.23. How is IO Communication done?
Code Meaning
Info << "Time = " << runTime.timeName() << nl << endl;
Info object is output to the screen
1.1.24. How are derivatives of fields evaluated?
Time derivative

Divergence (div)
Spatial derivative
Discretised using the flux at the faces
e.g. ∇⋅(uq) (the advection term)
Gradient (grad)
Spatial derivative
e.g. ∇p in the momentum equation
Laplacian
Spatial derivative

Discretised as ∇⋅μ∇q
gradient scheme for ∇q
interpolation for μ
discretisation for ∇⋅
e.g. μ∇2q in the momentum equation

1.1.25. What are the functions for discretisation?
Function Meaning
fvc::ddt(A)
fvm::ddt(A)
Time derivative
∂A/∂t
A can be a scalar, vector or tensor
fvc::ddt(rho,A)
fvm::ddt(rho,A)
Density weighted time derivative
∂ρA/∂t
ρ can be any scalar field
fvc::d2dt2(rho,A)
fvm::d2dt2(rho,A)
Second density weighted time derivative
∂/∂t(ρ∂A/∂t)
fvc::grad(A)
fvm::grad(A)
Gradient
A can be a scalar or a vector
Result is a volVectorField (from scalar) or a volTensorField (from vector)
fvc::div(A)
fvm::div(A)
Divergence
A can be a vector or a tensor
Result is a volScalarField (from vector) or a volVectorField (from tensor)
fvc::laplacian(A)
fvm::laplacian(A)
Laplacian
∇2A
fvc::laplacian(mu, A)
fvm::laplacian(mu, A)
Laplacian
∇⋅(μ∇A)
fvc::curl(A)
fvm::curl(A)
Curl
∇×A
fvm::div(phi,A)
Divergence using flux to evaluate this
A can be a scalar, vector or a tensor
fvm::Sp(rho,A)
Implicit evaulation of source term
fvm::SuSp(rho,A)
Implicit or explicit evaulation of source term (depending on sign of rho
1.1.26. How can are equations translated into code?
Equation Code
∂q∂t+∇⋅qu=μ∇2q
fvScalarMatrix transport
(
fvm::ddt(q)
+ fvm::div(phi,q)
- fvm::laplacian(mu,q)
);

// phi is the flux from the momentum equation
∂T∂t=κ∇2T
solve(fvm::ddt(T) == kappa*fvc::laplacian(T))

// T is a volScalarField defined on the mesh
// A discretised representation of the field variable T
// solve performs matrix inversion for one step
∂k∂t+∇⋅ku−∇⋅[(ν+νt)∇k]=νt[1/2(∇u+∇uT]2−ε/k
solve(
fvm::ddt(k)
+ fvm::div(phi,k)
- fvm::laplacian(nu()+nut,k)
== nut*magSqr(symm(fvc::grad(U)))
- fvm::Sp(epsilon/k,k)
);
1.1.27. How is the PISO algorithm programmed?
The PISO (Pressure Implicit with Splitting of Operators) is an efficient method to solve the Navier-Stokes equations

The algorithm can be summed up as follows:

Set the boundary conditions.
Solve the discretized momentum equation to compute an intermediate velocity field.
Compute the mass fluxes at the cells faces.
Solve the pressure equation.
Correct the mass fluxes at the cell faces.
Correct the velocities on the basis of the new pressure field.
Update the boundary conditions.
Repeat from 3 for the prescribed number of times.
Increase the time step and repeat from 1.
The implementation:

Define the equation for U
fvVectorMatrix UEqn
(
fvm::ddt(U)

fvm::div(phi, U) fvm::laplacian(nu, U)
);
Solve the momentum predictor
solve (UEqn == -fvc::grad(p));
Calculate the ap coefficient and calculate U
volScalarField rUA = 1.0/UEqn().A();
U = rUA*UEqn().H();
Calculate the flux
phi = (fvc::interpolate(U) & mesh.Sf()) fvc::ddtPhiCorr(rUA, U, phi);
adjustPhi(phi, U, p);
Define and solve the pressure equation and repeat for the prescribed number of non-orthogonal corrector steps
fvScalarMatrix pEqn
(
fvm::laplacian(rUA, p) == fvc::div(phi)
);
pEqn.setReference(pRefCell, pRefValue);
pEqn.solve();
Correct the flux
if (nonOrth == nNonOrthCorr)
{
phi -= pEqn.flux();
}
Calculate continuity errors include "continuityErrs.H"

Perform the momentum corrector step
U -= rUA*fvc::grad(p);
U.correctBoundaryConditions();
The following is from the OpenFOAM UK Users Group:

1.1.28. What are header files?
Sections of code in separate files that are widely used - all function prototypes in a header file

Equation Code
#include "CourantNumber.H"
File containing code for calculating Courant number
1.1.29. What is wmake?
wmake is a make system – directs the compiler to compile specific files in particular ways.

Controlled through files in Make:
files – specifies which user-written files to compile and what to call the result
options – specifies additional header files/libraries to be included in the compilation.

有些场数据完全不需要，比如ddt场，可以通过

find . -name "ddt*" -type f

确认删除的场，然后

find . -name "ddt*" -type f -delete

删除

参考 https://askubuntu.com/questions/377438/how-can-i-recursively-delete-all-files-of-a-specific-extension-in-the-current-di

按照文献中的案例模拟了一个三维方腔流
我的垂直速度曲线图和水平速度曲线图
BOT8L352FD5IWM~S5IFVX42.png MS0N{_5W.png
和实验结果不一样
QQ图片20190306104704.png
是什么原因造成的？

OpenFOAM手册第六章讲后处理。所有的数据都在文本里存着，所以这个后处理更像是取样（sample）。
用命令把速度数据提成单个文件，用其他后处理软件读取画图。
或者把扩展名改成cvs就可以用excel打开。在excel或者matlab里画。

如果OpenFOAM自带的命令满足不了你的需求。就搜linux上的文本处理软件，根据数据的特征（位置特征、前后缀特征）提取。

个人感觉fvPatchField是记录定义在网格体中心(cell center)的变量比如U在计算域边界上的值。fvsPatchField是记录定义在网格面中心(face center of cell)的变量比如phi，在计算域边界上的值。

@东岳 这个模型我很需要，请问东岳先生是用OF哪个版本的哪个求解器实现的？能否引入侧吹（也就是气泡从侧方吹入，而不是底部吹入）？

new cannot satisfy memory request. This does not necessarily mean you have run out of virtual memory. It could be due to a stack violation caused by e.g. bad use of pointers or an out of date shared library

如果你遇到这个问题，一种解决方式是把你的求解器重新编译一下，可能是bad use of out of date shared library。原因是你的库重新写了一些代码并重新编译了，但求解器没跟进

请教各位老师和同学一个问题：我在使用sprayFoam求解器的时候，想把液滴初次雾化模型 atomizationModel设置为LISA模型，请问该模型得到的液滴直径分布是否会和injectionModel中设置的初始粒径相互冲突吗，foam中是怎么处理的？

如题...

好吧！我先自己回复下自己。在稀疏矩阵存储中，通用有两种格式，如下矩阵

A = [ a00 a01 0 0 0 a11 a12 0 a20 0 a22 0 a30 0 0 a33];

引用一篇博士论文 CRS scheme stores the non-zero elements the matrix in left-to-right and top-to-bottom order in vector v (row-wise storge). 存储格式如下

v = [a00, a01, a11,a12,a20,a22,a30,a33] cI = [0,1,1,2,0,2,0,3] rI = [0,1,1,2,0,2,0,3]

但是在openfoam中，不是这么存储的
openfoam是一种 LDU 格式 对角线 lowerAddr() upperAddr()

A = [ d0 u0 u1 0 0 0 l0 d1 u2 0 0 0 0 l1 l2 d2 u4 u5 . . . ] l = [l0 l1 l2 ...] d = [d0 d1 d2 d3 d4 ...] u = [u0 u1 u2 u3 ...] L = [0 0 1 1 2 2 3 ...] U = [1 2 2 3 3 4 4 ..]

具体可参见lduAddressing.H 头文件
因为计算流体力学中，大部分矩阵都是对称（因为一个internal face对应两个体）除了特别的边界条件外，基本上都是对称矩阵。而矩阵对角元素就更好求了，大部分情况直接把该行相加就得到主对角元素。这种sparse matrix设计是符合cfd计算原理的，但是我的问题还是没解决。看到相关资料分享一下。
稀疏矩阵也分好多种，openfoam中的renumberMesh就是尽量保证在是多对角阵。
谢谢！

@东岳 好的，了解了！！谢谢您

在多区域（液体和固体换热）计算中，某一个物理量（温度T）在两个区域间的interface是一个连续的量，即没有热阻，这个interface边界条件该怎么设置？
在OpenFOAM自带的多区域算例中，这种耦合面用的边界条件是turbulentTemperatureCoupledBaffleMixed，这个其实是根据边界面的值是根据边界上的值来计算传热系数的，里面写的很麻烦，有点看不懂。有没有哪位老师指点一下？多谢多谢~

如题，OpenFOAM中有简单的命令可以快速实现吗？试过refineWallLayer，只能添加一层网格。

@东岳 第一次发帖求助，就能得到东岳老师的回复，真的非常感谢！
（1）是根据laplacianFOAM稍微改了下的求解器，但是如果是探针probe的话是可以运算出结果的。那cellSource不运行function的话，我需要怎么改下求解器吗
（2）还想请教下，算例边界条件设置的问题，左图是压力，右图是温度。
左图压力上下边界条件均为zero flux，右侧问题上下右边界条件为zero conductive flux。对于zero flux和zero conductive flux，边界条件是不是应设置为symmetryPlane，还是zeroGradient。我计算出的结果差别很大，不知道问题出在哪里，所以想确定下是不是我边界条件设置的不对。
case.JPG

@悬铃神木 谢谢。

@气固两相流 fluidisedBed.zip
是一个TFM算例的设置，烦请大神们帮忙看看算例有什么问题，不胜感激