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Old   June 26, 2009, 16:58
Question 3D mesh
  #41
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amin
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hi Dear Niklas

what is my mistake?
what is its correction?
how can i describe an axi-symmetric mesh for diesel foam?

I ran a 3D simulation of dieselfoam with last characteristic of n-heptane experiment and add its result to a new plot and attached it.

there are two strange things:
1- I saw some fluctuations in liquid penetration curve in 3D cases.
2- likewise liquid penetration is far from experimental result.
what is the reason of these?

I set the initial drop diameter to nozzle diameter according to injector model.is it correct?

I am confused.
Please help me.

thanks
regard
Attached Images
File Type: jpg 3D 2D.jpg (43.2 KB, 26 views)

Last edited by az1362f; June 27, 2009 at 11:31.
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Old   June 27, 2009, 13:35
Unhappy axi-symmetric Mesh
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Hi

I tried to solve last problem that I discussed in my last posts by axi-symmetric mesh but my results likewise were incorrect and far from experimental result.

I attached axi-symmetric Mesh.
please check my axi-symmetric blockmesh.
is it correct?
I tried to 3D simulation of dieselfoam of n-heptane experiment but results were far from experiment and had fluctuations.
Why are my result far from experiment?

please help me.
Thanks
regard
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File Type: jpg axi added.jpg (48.2 KB, 12 views)
Attached Files
File Type: zip blockMeshDict axisymmetric.zip (630 Bytes, 21 views)
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Old   June 29, 2009, 11:29
Default axi-symmetric Mesh
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Hi Dr Niklas

I tried to solve last problem that I discussed in my last posts by axi-symmetric mesh but my results likewise were incorrect and far from experimental result.

I attached axi-symmetric Mesh.
please check my axi-symmetric blockmesh.
is it correct?
I tried to 3D simulation of dieselfoam of n-heptane experiment but results were far from experiment and had fluctuations.
Why are my result far from experiment?

please help me.
Thanks
regard
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Old   June 30, 2009, 03:11
Question mesh dependency
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Hi Dr Niklas;

I tried to solve axi-symmetric dieselfoam for n-heptane fuel,and when I compare my result by experimental result I couldn't find a mesh size of dependency.
I attached my axi-symmetric mesh in last posts and new plot of liquid penetration:

Is my axi-symmetric mesh correct?
if yes why liquid penetration increased as mesh size is refined?

Thanks
Regard
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Old   June 30, 2009, 04:39
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Quote:
Originally Posted by az1362f View Post
Hi Dr Niklas;

I tried to solve axi-symmetric dieselfoam for n-heptane fuel,and when I compare my result by experimental result I couldn't find a mesh size of dependency.
I attached my axi-symmetric mesh in last posts and new plot of liquid penetration:

Is my axi-symmetric mesh correct?
if yes why liquid penetration increased as mesh size is refined?

Thanks
Regard
looks correct to me.

in general liquid penetration increase if you refine the mesh,
thats because you resolve the jet better and hence reduce the relative velocity.
You also have to investigate the influence on initial turbulent length scale, which also is
very important.
reducing the length scale will also increase the liquid penetration.
there are no ways around these problems for lagrangian/eulerian simulations.
you just have to live with the grid dependency.
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Old   July 1, 2009, 12:45
Default Validating spray
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Hi Dear Niklas;

then what is the way to validate spray simulation problem,when you don't know is your solution independent of mesh?

regard
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Old   July 4, 2009, 11:55
Default interpolation scheme
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Hi Dear Niklas;

Which interpolation scheme did you use for Inter-Phase Coupling in dieselfoam code?
Where can I see its implementation in dieselfoam code?
I attached two method of Inter-Phase Coupling,which one did you use in dieselfoam?

Thanks
Regard
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Old   July 6, 2009, 03:44
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none of them

http://www.nequam.se/files/thesis.pdf
page 34
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Old   July 7, 2009, 06:22
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Hi Dear NIklas;

Which of interpolation scheme did you used in dieselfoam?

equation 116 or equation 117:

if 117 how is it for Hexahedron cell?

thanks
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Old   July 8, 2009, 02:08
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in foam its always 117.

The cell is always split into a tet containing the parcel.
if you use cellPoint,
it will use the nodes and cell-center to construct the tet.

if you use cellPointFace it will use the nodes, cell center and face center to
construct the tet.
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Old   July 9, 2009, 10:44
Question implementation
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Hi Dear Niklas;

I am very thankful for your very good and complete answers.

I have a question about where is the implementation of eq.117 in Foam?

also,I studied your article by subject of "Numerical Investigation of Mesh/Turbulence/Spray
Interaction for Diesel applications",you talked in this article about limiting turbulenc lengh scale, is it limited in openfoam 1.5 for dieselfoam?
if no, where can i limit it?

Thanks
Regard

Last edited by az1362f; July 11, 2009 at 17:34. Reason: adding new question
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Old   July 11, 2009, 17:44
Default turbulent length scale
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Hi Dear Niklas;

I am very thankful for your very good and complete answers.

I have a question about where is the implementation of eq.117 in Foam?

also,I studied your article by subject of "Numerical Investigation of Mesh/Turbulence/Spray Interaction for Diesel applications",you talked in this article about limiting turbulenc length scale, is it limited in openfoam 1.5 for dieselfoam?
if no, where can i limit it in the code according your article?

Thanks
Regard
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Old   July 13, 2009, 11:09
Question turbulence length scale
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Hi Dear Niklas;

I am very thankful for your very good and complete answers.

I have a question about where is the implementation of eq.117 in Foam?

also,I studied your article by subject of "Numerical Investigation of Mesh/Turbulence/Spray Interaction for Diesel applications",you talked in this article about limiting turbulence length scale, is it limited in openfoam 1.5 for dieselfoam?
if no, where can i limit it in the code according your article?

Thanks
Regard
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Old   July 20, 2009, 04:51
Question finding parcel
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Hi to all,

any body knows how openfoam check the existence of particle in an eulerian cell?
in the other word which function or class find if there is a parcel in the current cell?
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Old   July 22, 2009, 12:51
Default limiter
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Hello Dear Dr Nordin;

I saw in RASProperties file that for K-epsilon model there are two parameters for limiter :" muLimiter on;Lsgs 0.0002;

are these parameters activate turbulent length scale limiter in openFoam version 1.5?

please answer me.
thanks

regard
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Old   September 25, 2009, 22:44
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Hi,az1362f and other foamers
i also want to know how to caculate the liquid penetration length,and how i can change the liquid
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Old   September 28, 2009, 11:32
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Hi,

i use octave/matlab to calculate penetration length. the position of the parcel you can find in $FOAM_CASE/timeDirectory/lagrangian/defaultCloude/position.
The liquid is defined in $FOAM_CASE/thermophysicalProperites

Christof
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Old   October 1, 2009, 06:23
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Quote:
Originally Posted by chbenz View Post
Hi,

i use octave/matlab to calculate penetration length. the position of the parcel you can find in $FOAM_CASE/timeDirectory/lagrangian/defaultCloude/position.
The liquid is defined in $FOAM_CASE/thermophysicalProperites

Christof
Hi,
i have found the "position" file ,but i want to know how to calculate penetration length.Thank you very much,Christof
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Old   October 26, 2011, 04:12
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Quote:
Originally Posted by az1362f View Post
hi

I implemented these line in dieselfoam solver to save liquid peneteration lenght in every time step,but my result showed an approximately a constant liquid penetration.(for example 10.xxxx)

std :: fstream penet
penet.open("penetration.txt",std::ios::app);
penet << dieselSpray.liquidPenetration(1.0)<<"\t"<<runTime. timeName()<<"\n"<<endl;
penet.close();

what is my mistake?
I used default setting of dieselfoam tutorials.
I attached a penetration result.
please help me.

Hello Amin,

how did you implement this function can you share it, i m having this problem to implement in dieselFoam
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Old   June 12, 2012, 22:42
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hi dude,I confront a problem similar to yours now, where should I go to for changing the chem.inp and therm.dat files?
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