Fluid-Structure Mesh

Altair Forum User

Hi every body

I need your help. I want to run a model like the Half car model in the tutorial with Fuid and Strukture Elements.

I always get this Error: 'ERROR # 1684: FLUID element     4493 points to non-fluid GRID   1900'

Taht i dont know how to manage.

My modell is a cube and the Fluid Elements are tetraeder wen the Structure elements are trias.

Altair Forum User

Is any answer available for same question.. even I am facing same problem.

Altair Forum User

Hi Mitesh Parmar,

 

When doing a Coupled fluid structural analysis, you need to differentiate fluid grids by setting CD= -1.

 

Select all the grids (nodes) which are part of fluid, Card edit those nodes and set CD to -1 as shown in the image below and run the analysis:

 

 

<?xml version="1.0" encoding="UTF-8"?>

Unknown

Hi Prakash and thanks for the reply

 

I am facing the same problem and since I am relatively new to Optistruct I cant seem to find the way to assign CD-1. Could you maybe give more step by step explenation how to set CD to -1.

 

Many thanks,

 

Uroš

Altair Forum User

Hi @uros

 

Select all the grids which you want to make as fluid and use the card edit icon to edit the Nodes.

<?xml version="1.0" encoding="UTF-8"?>

Unknown

Thanks @Prakash Pagadala. It works. You are the best

 

 

Unknown

Hi again @Prakash Pagadala. I made the trick you proposed and it worked for the acoustic medium. Now I am facing a similar error between the structure and the fluid elements.

I try to do the same trick, setting CD to -1 but it doesnt semes to work.

----------------------------------------

 

Job load: 1

hwsolver.mesg output from the solver:

==============================

 *** ERROR 1686: STRUCTURE element    64568 points to fluid GRID  43113.

 

---------------------------------------------------------

 

Sorry to bother you and thanks for help in advanced.

 

Regards,

 

Uroš

 

 

 

 

 

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi,

 

You need to detach the fluid and structure components or else you will get the following errors related to the nodes which are shared by both the fluid and structure comps. You can use detach option in 2D/3D pages to detach structural elements from fluid elements. 

Unknown

Hi @Prakash Pagadala, thanks again for the help. I was able to detach the 3D elemets. As you can see on the picture there are two nodes at the interface. Saddy I still get the same error. Do you have any other idea maybe?

 

Thanks again,

 

Uroš

<?xml version="1.0" encoding="UTF-8"?>