[Robert_B]

Hi all

I am trying to find a way to stretch my mesh dimensions by small amounts in various directions.

I am modelling a pulsejet, with shape similar to this one:
http://www.google.co.uk/imgres?q=cal...t:429,r:4,s:54

I have built an unstructured tetrahedral mesh, and it seems to modelling the pulsejet's operation well.

I now want to make small alterations to the pulsejet's dimensions, and examine the effect of these alterations on its performance. So for example, I would like to alter the length of the inlet pipe by 5% (say), while leaving all other dimensions unchanged.

I want to make these alterations, without having to build a new tetrahedral mesh from scratch. Rather I want to take my existing mesh, and stretch or compress various parts of it, to achieve the desired alteration in dimensions. The number of cells and their relative positions should remain unchanged.

The program I am using is StarCD, but it does not seem to have a facility for stretching sections of mesh. So I would like to know if there is a good program that I could use to stretch sections of my mesh?

I can export my mesh in the following formats: Ansys, Nastran, ICEM, STL, Patran, Ideas, pro-STAR. Hopefully there will be a program that can take a mesh saved in one of these formats, and perform the desired stretching operations. I could then import the altered mesh back into StarCD.

Can anyone help by recommending a program that can perform the stretching operations I have described?

[sail]

Originally Posted by Robert_B

Hi all

I am trying to find a way to stretch my mesh dimensions by small amounts in various directions.

I am modelling a pulsejet, with shape similar to this one:
http://www.google.co.uk/imgres?q=cal...t:429,r:4,s:54

I have built an unstructured tetrahedral mesh, and it seems to modelling the pulsejet's operation well.

I now want to make small alterations to the pulsejet's dimensions, and examine the effect of these alterations on its performance. So for example, I would like to alter the length of the inlet pipe by 5% (say), while leaving all other dimensions unchanged.

I want to make these alterations, without having to build a new tetrahedral mesh from scratch. Rather I want to take my existing mesh, and stretch or compress various parts of it, to achieve the desired alteration in dimensions. The number of cells and their relative positions should remain unchanged.

The program I am using is StarCD, but it does not seem to have a facility for stretching sections of mesh. So I would like to know if there is a good program that I could use to stretch sections of my mesh?

I can export my mesh in the following formats: Ansys, Nastran, ICEM, STL, Patran, Ideas, pro-STAR. Hopefully there will be a program that can take a mesh saved in one of these formats, and perform the desired stretching operations. I could then import the altered mesh back into StarCD.

Can anyone help by recommending a program that can perform the stretching operations I have described?

i don't think you can simply strech a mesh.

what i would reccomand would be to create the mesh and the geometry with a script-able software. in this way you can recreate the mesh with the modified geometry with just a couple of clicks/commands.

most of softwares can do this, pointwise, gambit, icem are just the first that comes to mind.

of course this make sense if you have to run lot of simulations with differences in the geometry. in case of a sinle run with just a 5% inlet lenght, you might try some workaround like using interfaces, and so on. If it is the case, i'm afraid i can't help you because i'm not proficent with starCd.

good luck.

[JBeilke]

Originally Posted by Robert_B

The program I am using is StarCD, but it does not seem to have a facility for stretching sections of mesh. So I would like to know if there is a good program that I could use to stretch sections of my mesh?

StarCD can definately do what you want. Have a look at the vscale command.