valve directed by pressure

flo90000 · May 10, 2016, 10:36

Hello

I want to write an UDF who moves a valve in function of the pressure around it. But I don't know how to do it in function of the pressure applied or if I should write a pivoting link between the valve and the support and the pressure will move the valve directly.

Thanks for your advices or help.

pakk · May 11, 2016, 03:28

There is no need to ask exactly the same question three times.

Edit: the two other threads have since been removed.

`e` · May 11, 2016, 04:08

You could move the valve as a function of the pressure in the fluid by using the dynamic mesh (moving/deforming mesh model). Specifically, use the DEFINE_GRID_MOTION macro and displace the valve boundary nodes as a function of the local pressure (with the C_P macro). Take care to ensure a high mesh quality is conserved throughout your simulation; use deforming for small valve displacements and enable remeshing should your geometry change significantly.

flo90000 · May 23, 2016, 05:07

Quote:

Originally Posted by `e`

You could move the valve as a function of the pressure in the fluid by using the dynamic mesh (moving/deforming mesh model). Specifically, use the DEFINE_GRID_MOTION macro and displace the valve boundary nodes as a function of the local pressure (with the C_P macro). Take care to ensure a high mesh quality is conserved throughout your simulation; use deforming for small valve displacements and enable remeshing should your geometry change significantly.

Hello

thanks for your answer `e`. I am a beginner in the using of UDF so I searched how to use the DEFINE_GRID_MOTION macro with the C_P macro. Is it possible to have an example?

`e` · May 23, 2016, 07:08

The UDF manual is a good place to start learning how to code user-defined functions as they describe what each function does and also provides examples. C_P is a flow variable macro which retrieves the local cell pressure (it's not specific to the dynamic mesh). The example in the manual for the grid motion describes the deflection of a cantilever beam (start with this example and then change the dependent variable to pressure).

May 10, 2016, 10:36	valve directed by pressure	#1
flo90000 Member ERMACORA Florian Join Date: May 2016 Posts: 39 Rep Power: 9	Hello I want to write an UDF who moves a valve in function of the pressure around it. But I don't know how to do it in function of the pressure applied or if I should write a pivoting link between the valve and the support and the pressure will move the valve directly. Thanks for your advices or help.

May 11, 2016, 03:28		#2
pakk Senior Member Join Date: Nov 2013 Posts: 1,965 Rep Power: 26	There is no need to ask exactly the same question three times. Edit: the two other threads have since been removed. Last edited by pakk; May 11, 2016 at 09:19.

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May 11, 2016, 04:08		#3
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	You could move the valve as a function of the pressure in the fluid by using the dynamic mesh (moving/deforming mesh model). Specifically, use the DEFINE_GRID_MOTION macro and displace the valve boundary nodes as a function of the local pressure (with the C_P macro). Take care to ensure a high mesh quality is conserved throughout your simulation; use deforming for small valve displacements and enable remeshing should your geometry change significantly.

May 23, 2016, 07:08		#5
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	The UDF manual is a good place to start learning how to code user-defined functions as they describe what each function does and also provides examples. C_P is a flow variable macro which retrieves the local cell pressure (it's not specific to the dynamic mesh). The example in the manual for the grid motion describes the deflection of a cantilever beam (start with this example and then change the dependent variable to pressure).