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Hi everybody,

I'm new using telemac and I do not very well how to modify subroutines.

I want to model the presence of vertical structures in individual nodes which are located in different places of the domain. For this reason I do not want to use INPOLY as is the case in the dragfo.f subroutine example.

How can I define a node or a set of nodes in the dragfo.f subroutine instead of using INPOLY function?

Thank you.

Regards,

Eduardo

Hi

Dragfo subroutine is an example. The call to inpoly exist in order to identify which are the nodes where the drag force should be apply.

You could also directly give the node number if you want...
But you should keep in mind that during parallel computation, the partitionning step leads to a renumbering of the nodes in each subdomain so this solution is not possible...

Hope this helps

Hi C.Coulet,

Thank you for your fast respone and advice with parallelisation.

Would you mind to show me how is the command line to call a node, please?

I just satrt with Telemac and I'm a little bit lost.

Thank you very much.

Regards,

Eduardo

Hi
I don't know exactly what you want to do but if you manage to use dragfo but you don't have to use a polygon definition to apply the drag force you could directly give the wanted value to the identified node.
Something like FUDRAG%R(mynode)= xxx and FVDRAG%R(mynode)= yyy

hope this helps

Hi C.Coulet,

Thank you for your response.

I just want to define drag forces as a function of velocitys due to a bridge pier in specific nodes not areas.

I tried the procedure you told me but looks like nothing is happening. Attached you could find the dragfo.f subroutine. Please check it and let me know if it is correct.

Another question is: what is the purpose of the following command line in the dragfo.f subroutine?

AIRE = AIRE + T1%R(I)

Regards,

Eduardo

Hello,

Did you look at the Telemac-2D example called dragforce ? It does most probably what you want to do.

The total drag force due to the pier is spread over an area, this is why we need to compute AREA. T1%R is the result of a call to subroutine VECTOR with formula 'MASBAS' which means in Telemac pidgin that it is the integral of test functions, which can be considered as an area around points (the sum of all these areas is the area of the domain). See the guide for programming in the Telemac system on this site to have more details.
The line AREA = AREA + T1... computes the area of the zone where the drag forces are applied (these drag forces will really make a force when they are multiplied by an area, which is what does then the finite element variational formulation). You need to consider the momentum equations which are written du/dt=... to understand that all this is dimensionally correct.

Que le vaya bien !

Jean-Michel Hervouet

Merci beaucoup!