external flow over a sphere RADIOSS

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi !

I'm trying to find the drag force of the air on a sphere. I'm using MLAW6 with the k-epsilon model on a tetramesh for the air, and M11 BOUND for the bound on a cubic mesh, the sphere is meshed with shells and put in a rigidbody.

I chose an eulerian formulation (i also tried ALE..)ter

I imposed a velocity of 10m/s on the first row of nodes of the air.

I used the interface TYPE18 with a gap larger than 1.5times the element size to be sure it works. Master : sphere, slave : air

But i still have the error : TIME STEP LESS OR EQUAL DTMIN FOR SOLID ELEMENTS

 

This is strange because when the air is meshed using a cubic mesh it works quite well  (even though i usually get a drag force about twice as large as what i calculated myself with the formula)

 

Any ideas why it doesnt work ? and how i could make it work ?

 

Thanks

 

Matt

 

 

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