Incompressible Flow Pre-Processing

drdopamine · August 28, 2020, 03:39

Hello all,

My name is Bobby and I work for a company that does Model / Hobbyist rockets. I'm trying to learn openFOAM to improve some of the content I can make for them.
I have no educational background in this field, and prior to this I'd never even opened linux.

Anyway, on to what I am trying to do. I intend to use an incompressible flow solver to analyze a model rocket (specifically a modified X-15).

I've duplicated the motorbike tutorial and created my own case. I've taken an .obj of the X15 and compressed it to match the format (.obj.gz), then replaced that with the root motorbike.obj.gz.

Then I ran the Allrun. I know, ignorant / wishful thinking.

I'm an amature, but it would appear to error out during the reconstructPar sequence, and according to the log

From function int main(int, char**)
in file reconstructPar.C at line 256
No times selected

However I cannot find reconstructPar.C anywhere in the case. This, I believe is my first problem?

Through further research I can tell I am also going to need to edit the blockMeshdict, as the .obj for the X15 is to scale dimensions, being FAR smaller than the motorbike. When looking into the blockMeshdict, I can see a series of vertices, blocks and boundaries that I imagine make up a rectangular prism similar to a windtunnel.

Is there an easy way to scale this down? Or a resource you can point me to which can define everything I am looking at? I checked the users-guide but to no avail (maybe I just couldn't find it?)

Lastly, what else am I overlooking? I'm sure there are other things. If there are barriers you forsee ahead of me, I'd love to know.

Thanks so much for your time.

simrego · September 3, 2020, 05:32

Hi!

Based on your post I think you should start here:
https://cfd.direct/openfoam/user-guide/
There are some chapters about coding and I think you can skip this part. But you should at least run through the whole doc once. So you will have an idea what's happening and what is the "methodology" behind OpenFOAM.

BTW scale what? The background mesh? In the blockMeshDict you have a scale entry. But you can also scale the final mesh which is the result of snappyHexMesh with the transformPoints utility.

August 28, 2020, 03:39	Incompressible Flow Pre-Processing	#1
drdopamine New Member Bobby Join Date: Aug 2020 Posts: 1 Rep Power: 0	Hello all, My name is Bobby and I work for a company that does Model / Hobbyist rockets. I'm trying to learn openFOAM to improve some of the content I can make for them. I have no educational background in this field, and prior to this I'd never even opened linux. Anyway, on to what I am trying to do. I intend to use an incompressible flow solver to analyze a model rocket (specifically a modified X-15). I've duplicated the motorbike tutorial and created my own case. I've taken an .obj of the X15 and compressed it to match the format (.obj.gz), then replaced that with the root motorbike.obj.gz. Then I ran the Allrun. I know, ignorant / wishful thinking. I'm an amature, but it would appear to error out during the reconstructPar sequence, and according to the log From function int main(int, char**) in file reconstructPar.C at line 256 No times selected However I cannot find reconstructPar.C anywhere in the case. This, I believe is my first problem? Through further research I can tell I am also going to need to edit the blockMeshdict, as the .obj for the X15 is to scale dimensions, being FAR smaller than the motorbike. When looking into the blockMeshdict, I can see a series of vertices, blocks and boundaries that I imagine make up a rectangular prism similar to a windtunnel. Is there an easy way to scale this down? Or a resource you can point me to which can define everything I am looking at? I checked the users-guide but to no avail (maybe I just couldn't find it?) Lastly, what else am I overlooking? I'm sure there are other things. If there are barriers you forsee ahead of me, I'd love to know. Thanks so much for your time.

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September 3, 2020, 05:32		#2
simrego Senior Member anonymous Join Date: Jan 2016 Posts: 416 Rep Power: 14	Hi! Based on your post I think you should start here: https://cfd.direct/openfoam/user-guide/ There are some chapters about coding and I think you can skip this part. But you should at least run through the whole doc once. So you will have an idea what's happening and what is the "methodology" behind OpenFOAM. BTW scale what? The background mesh? In the blockMeshDict you have a scale entry. But you can also scale the final mesh which is the result of snappyHexMesh with the transformPoints utility.