Cornering Flow Boundary Conditions (OpenFoam)

CfdIntro · February 1, 2018, 08:49

Hi, I'm interested in examining the aerodynamic effects of cornering flow on an FSAE car. After searching online, I came up to the conclusion that this (Fig.1) type of mesh would be the most beneficial for the simulation.

Fig.1

The issue now is how can someone assign two boundary conditions on the same field of a mesh for use in OpenFoam? As you can see, there is one "inlet" bc and one "outlet" bc on the same field.

Any thoughts on how it can be done? Any other tip on cornering flow simulations would be greatly appreciated! Thanks in advance!

piu58 · February 1, 2018, 11:35

An easy way is to divide the area in strips. For every Strip you can set the b.c. you need.

Anothe way ist to use curved boundary and to have only an inlet and an outlet and two walls.

CfdIntro · February 1, 2018, 18:43

Quote:

Originally Posted by piu58

Anothe way ist to use curved boundary and to have only an inlet and an outlet and two walls.

This was my initial approach to the cornering flow case but I quickly realized that a new mesh would be needed every time one of the parameters change, i.e. the curvature of the flow. Having a rectangular mesh with the boundary conditions assigned as described on the first post, actually saves time because the same mesh can be used for simulations with different parameters.

Quote:

Originally Posted by piu58

An easy way is to divide the area in strips. For every Strip you can set the b.c. you need.

How can I divide the area in strips? This is actually what I have in mind as the solution to the cornering flow problem.

Thanks in advance!

piu58 · February 2, 2018, 00:27

Quote:

Originally Posted by CfdIntro

How can I divide the area in strips? This is actually what I have in mind as the solution to the cornering flow problem.

Thanks in advance!

This is simple : Create three strips with blockmesh, and define eight boundary areas form them.

CfdIntro · February 2, 2018, 08:59

Quote:

Originally Posted by piu58

Create three strips with blockmesh

I've been searching online about how to create strips with blockmesh to no avail. Is there any chance you could provide us with a series of bullet points on how to do it? It would be really helpful!

Thanks for the suggestion!

piu58 · February 2, 2018, 12:21

I recommend strongly to look at the examples which are delivered with OpenFoam. I cannot describe the usage of blockMesh with a few words.

OF has a manual which should be included in the installation. It describes the usage of blockMesh.

CfdIntro · February 2, 2018, 14:57

Quote:

Originally Posted by piu58

I recommend strongly to look at the examples which are delivered with OpenFoam. I cannot describe the usage of blockMesh with a few words.

OF has a manual which should be included in the installation. It describes the usage of blockMesh.

Problem solved, I misunderstood the meaning of the word "strip".

AMR96 · March 16, 2023, 08:42

Quote:

Originally Posted by piu58

This is simple : Create three strips with blockmesh, and define eight boundary areas form them.

Hi Uwe,

I know this is a really old case but it would mean a lot if you could help me with my question.

I am trying to simulate this exact case, my idea is to create a rectangular domain with the the inlets and outlets as indicated in the picture and then rotate the domain around an external point. But I am not exactly sure how that can be done, is this possible by using MRF or is there another Openfoam function that I have to use to do this.

Best,

Amirmohammad

piu58 · March 17, 2023, 02:44

I don't know any tool which rotates a mesh. But it may be, there is one.

I recommend modifying the blockmesh file itself, or may be easier, generate it from a small program. This program may have all parameters as input and you could automate your simulations.

Yann · March 17, 2023, 03:44

Quote:

Originally Posted by AMR96

Hi Uwe,

I know this is a really old case but it would mean a lot if you could help me with my question.

I am trying to simulate this exact case, my idea is to create a rectangular domain with the the inlets and outlets as indicated in the picture and then rotate the domain around an external point. But I am not exactly sure how that can be done, is this possible by using MRF or is there another Openfoam function that I have to use to do this.

Best,

Amirmohammad

Hello Amirmohammad,

Maybe you could use SRF for this.
Have a look at SRFSimpleFoam/SFRPimpleFoam.

Regards,
Yann

AMR96 · March 23, 2023, 10:24

Thanks for your message Uwe,

I also think it would be best to mesh with another software and bringing it to OpenFOAM.

Best,

Amirmohammad

AMR96 · March 23, 2023, 10:25

Thanks Yann,

After reading the relevant documents, I think this is what I have been searching for.

Best,

Amirmohammad

February 1, 2018, 08:49	Cornering Flow Boundary Conditions (OpenFoam)	#1
CfdIntro New Member Join Date: Oct 2017 Posts: 15 Rep Power: 8	Hi, I'm interested in examining the aerodynamic effects of cornering flow on an FSAE car. After searching online, I came up to the conclusion that this (Fig.1) type of mesh would be the most beneficial for the simulation. Fig.1 The issue now is how can someone assign two boundary conditions on the same field of a mesh for use in OpenFoam? As you can see, there is one "inlet" bc and one "outlet" bc on the same field. Any thoughts on how it can be done? Any other tip on cornering flow simulations would be greatly appreciated! Thanks in advance!

February 1, 2018, 11:35		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	An easy way is to divide the area in strips. For every Strip you can set the b.c. you need. Anothe way ist to use curved boundary and to have only an inlet and an outlet and two walls. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

February 2, 2018, 12:21		#6
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	I recommend strongly to look at the examples which are delivered with OpenFoam. I cannot describe the usage of blockMesh with a few words. OF has a manual which should be included in the installation. It describes the usage of blockMesh. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

March 17, 2023, 02:44		#9
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	I don't know any tool which rotates a mesh. But it may be, there is one. I recommend modifying the blockmesh file itself, or may be easier, generate it from a small program. This program may have all parameters as input and you could automate your simulations. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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March 23, 2023, 10:24		#11
AMR96 Member Join Date: Apr 2022 Posts: 31 Rep Power: 4	Thanks for your message Uwe, I also think it would be best to mesh with another software and bringing it to OpenFOAM. Best, Amirmohammad

March 23, 2023, 10:25		#12
AMR96 Member Join Date: Apr 2022 Posts: 31 Rep Power: 4	Thanks Yann, After reading the relevant documents, I think this is what I have been searching for. Best, Amirmohammad