code_saturne User's Forum

Hello Yvan

I am still making progress in the development of the BC. However, I figurd out that the flow given by the UDF makes no physical sense. The code (cs_user_BC.f90) is as follows :

s_tot = 0.d0
sumpre = 0.d0
call getfbr('outlet', nlelt, lstelt)
do ilelt = 1, nlelt

ifac = lstelt(ilelt ...

Hello Yvan

As suggested in your posting, I added the following lines to cs_user_parameters.f90.
subroutine usipsu &
( nmodpp )

!===============================================================================
! Module files ...

Thank you Yvan for detailed explanation.
Since I am dealing with derivative terms (d/dt) for both pressure and flow rate, I need at least two values at current and previous time steps to set the BC. That is the reason I am trying to get access to previous values ( t =0 and -1 or -2 here).

It ...

Hi Yvan,
I was digging in the doxygen document and I found the following modules to retrieve fields values at the preveious time step, e.g for pressure :

! INITIALIZATION
call field_set_n_previous(ivarfl(ipr),1)
call field_get_val_prev_s(ivarfl(ipr), press_temp)
then
pretem = press_temp(ifac ...

Hi Yvan

Thank you for your response.

If the UDF run is terminated before the current time step, there is definitely no need for data at the previous time step.
Anyways, I will test your recommendations, and I will keep you informed of progress. It may help other users of Code_Saturne in the ...

Hello there

is it possible to implement a three element Windkessel type outlet boundary condition with code_saturne?
To do so, I need to model a pressure-flow coupled boundary Condition. Here, a pressure outlet BC must be used, but its value depends on pressure and flow at previous time step (to ...