[zxj160]

Hello everyone,

I am a beginning user of funkySetFields utility. I want to set the cyclic velocity BC from the inlet to outlet with pressure gradient. I have questions:

1. Can I define the patch type as cyclic or the general patch in the blockMeshDict?

2. If I want to set the U and P field using the funkySetFields utility, is it necessary to set these first in '0' directory. Then using funkySetFields.

3. What about funkySetBoundayFields?
http://openfoamwiki.net/index.php/Co...funkySetFields

4. Is there any tutorials about the funkySetFields or sample cases of it?

[gschaider]

Originally Posted by zxj160

Hello everyone,

I am a beginning user of funkySetFields utility. I want to set the cyclic velocity BC from the inlet to outlet with pressure gradient. I have questions:

1. Can I define the patch type as cyclic or the general patch in the blockMeshDict?

2. If I want to set the U and P field using the funkySetFields utility, is it necessary to set these first in '0' directory. Then using funkySetFields.

3. What about funkySetBoundayFields?
http://openfoamwiki.net/index.php/Co...funkySetFields

4. Is there any tutorials about the funkySetFields or sample cases of it?

@1: Yes. cyclic is specified in the blockMeshDict. See the UserGuide

@2: Your question is "Do I have to create an U-file before setting the initial condition with FSF?", right? Answer: You don't have to (use the -create-option), but then you'll probably have to edit the resulting file to get decent boundary conditions

@3: that can be used to set arbitrary static boundary conditions (if you don't want to use groovyBC). There is an example file in the swak-Distro. Also see @4

@4: The only thing that resembles a tutorial is the presentation found at http://openfoamwiki.net/index.php/Co...er_information (also with a usage example of funkySetBoundaryFields if I remember it correctly)

Concerning your "cyclic U and jump in p": there is a boundary condition "fan" in OF that can be used for that, I think. Never had to use it yet, so you'll have to see yourself. There is also a similar BC called groovyBCJump in swak4Foam

[zxj160]

Many thanks for your reply.

I have tried FSF to set the initial field. But I met a problem:

funkySetFields -create -field U -expression "vector(log((pos().y-10+0.0003)/0.0003),0,0)" -time 0 -condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20" -dimension "[0 1 -1 0 0 0 0]"

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 2.1.0-0bc225064152
Exec : funkySetFields -create -field U -expression vector((0.02/0.0003)*log((pos().y-10+0.0003)/0.0003),0,0) -time 0 -condition pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20 -dimension [0 1 -1 0 0 0 0]
Date : Feb 27 2012
Time : 20:02:08
Host : "zxj160-laptop"
PID : 1818
Case : /home/zxj160/pisolestest
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Time = 0
Using command-line options

Creating field U

Putting "vector((0.02/0.0003)*log((pos().y-10+0.0003)/0.0003),0,0)" into field U at t = "0" if condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20" is true

#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 log in "/lib/tls/i686/cmov/libm.so.6"
#4 Foam::log(Foam::Field<double>&, Foam::UList<double> const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::log<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/lib/libswak4FoamParsers.so"
#6 parserField::FieldValueExpressionParser:arse() at FieldValueExpressionParser.C:0
#7 Foam::FieldValueExpressionDriver:arse(std::strin g const&) in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/lib/libswak4FoamParsers.so"
#8
in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/bin/funkySetFields"
#9
in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/bin/funkySetFields"
#10 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#11
in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/bin/funkySetFields"
Floating point exception
zxj160@zxj160-laptop:~/pisolestest$ funkySetFields -create -field U -expression "vector(log((pos().y-10+0.0003)/0.0003),0,0)" -time 0 -condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20" -dimension "[0 1 -1 0 0 0 0]"

Create time

Create mesh for time = 0

Time = 0
Using command-line options

Creating field U

Putting "vector(log((pos().y-10+0.0003)/0.0003),0,0)" into field U at t = "0" if condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20" is true

#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 log in "/lib/tls/i686/cmov/libm.so.6"
#4 Foam::log(Foam::Field<double>&, Foam::UList<double> const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::log<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/lib/libswak4FoamParsers.so"
#6 parserField::FieldValueExpressionParser:arse() at FieldValueExpressionParser.C:0
#7 Foam::FieldValueExpressionDriver:arse(std::strin g const&) in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/lib/libswak4FoamParsers.so"
#8
in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/bin/funkySetFields"
#9
in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/bin/funkySetFields"
#10 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#11
in "/home/zxj160/OpenFOAM/zxj160-2.1.0/platforms/linuxGccDPOpt/bin/funkySetFields"
Floating point exception


But when I run: funkySetFields -create -field U -expression "vector((pos().y-10+0.0003)/0.0003,0,0)" -time 0 -condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20" -dimension "[0 1 -1 0 0 0 0]" , it is OK.

I want to know the error of my previous expression: vector(log((pos().y-10+0.0003)/0.0003),0,0).

[gschaider]

Originally Posted by zxj160

But when I run: funkySetFields -create -field U -expression "vector((pos().y-10+0.0003)/0.0003,0,0)" -time 0 -condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20" -dimension "[0 1 -1 0 0 0 0]" , it is OK.

I want to know the error of my previous expression: vector(log((pos().y-10+0.0003)/0.0003),0,0).

Have a look at the stack-traces: the problem occurs when evaluating the logarithm. The logarithm for a negative number is undefined. If you have in your mesh cells with y<(10-0.0003) then this is the case

[zxj160]

Originally Posted by gschaider

Have a look at the stack-traces: the problem occurs when evaluating the logarithm. The logarithm for a negative number is undefined. If you have in your mesh cells with y<(10-0.0003) then this is the case

Yes, that may be the problem, but I has defined the conditions? How can I do achieve that log expression?

I also want to set : funkySetFields -field U -expression "(0,0,0)" -time 0 -keepPatches -condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20".

[zxj160]

Another question is that "can funkySetFields be used to create a uniform field". I want to keep the velocity in the some parts of the domain uniforma.

[gschaider]

Originally Posted by zxj160

Yes, that may be the problem, but I has defined the conditions? How can I do achieve that log expression?

I also want to set : funkySetFields -field U -expression "(0,0,0)" -time 0 -keepPatches -condition "pos().x>0 && pos().x<30 && pos().y>10 && pos().y<20".

Ah. Sorry. Just seen that. OK. In theory you guarded against that. The problem is that the expression is evaluated for the whole domain (that's where the problem occurs) and then values are picked according to the condition (so it comes to late). So you'll have to modify the log calculation to something like

log(max((pos().y-10+0.0003)/0.0003),1),0,0)

[gschaider]

Originally Posted by zxj160

Another question is that "can funkySetFields be used to create a uniform field". I want to keep the velocity in the some parts of the domain uniforma.

Of course. If the expression yields a uniform field ... "vector(max(pos().y),0,0)" for instance (not that it makes much sense)

Of what do you mean with "keep uniform"?

[zxj160]

Originally Posted by gschaider

So you'll have to modify the log calculation to something like

log(max((pos().y-10+0.0003)/0.0003),1),0,0)

Fantastic. This can solve the problem. Many thanks.

[zxj160]

Originally Posted by gschaider

Of course. If the expression yields a uniform field ... "vector(max(pos().y),0,0)" for instance (not that it makes much sense)

Of what do you mean with "keep uniform"?

Yes, I want to keep the some field uniform when running the code. I use the LES model.

[gschaider]

Originally Posted by zxj160

Yes, I want to keep the some field uniform when running the code. I use the LES model.

So in a certain region you want to override the solution? I don't endorse this kind of thing (violation of all kinds of conservation), but support it via swak4Foam (I'm that kind of irresponsible person):

- the swakFunctionObjects-library has a functionObject manipulateField. Field is reset at the end of each time-step. This requires no modification of the solver. As you've mastered FSF you'll be comfortable with the expression/condition-semantics
- the forceEquation-class in the swakSourceFields allows fixing a field in certain regions. This requires modifications of the solver. See the example-solver interFoamWithFixed and discussions about expressionSource elsewhere here on the forum

[zxj160]

Actually, I want to make the velocity outcome like the attached picture (from website). The upper region of the canyon is uniform. The inlet and outlet is cyclic. I do not know how to do that. Is it possible to calculate the different region with different turbulent model (laminar and LES)? Could you suggest me some ideas? Many thanks.

[gschaider]

Originally Posted by zxj160

Actually, I want to make the velocity outcome like the attached picture (from website). The upper region of the canyon is uniform. The inlet and outlet is cyclic. I do not know how to do that. Is it possible to calculate the different region with different turbulent model (laminar and LES)? Could you suggest me some ideas? Many thanks.

The picture doesn't make it clearer for me (for instance: which regions should be uniform ... etc)

I don't think that the laminar/LES-questions fits the topic of this thread