# Calculation of pressure gradient in periodic boundary condition

 Register Blogs Members List Search Today's Posts Mark Forums Read

 May 12, 2011, 09:00 Calculation of pressure gradient in periodic boundary condition #1 New Member   Ksaati Join Date: Oct 2010 Posts: 5 Rep Power: 14 Hi I am a student and i'm doing my project work in FLUENT. Simulation of flow over circular cylinder is to be done. Material is water. Computational domain is rectangular. inlet is taken as velocity inlet and outlet as pressure-outlet. Top and bottom boundary condition is periodic. how do i calculate pressure gradient which is necessary to input in transitional periodic condition? How do i get the value of period? Somebody kindly help me. It is extremely urgent.... Please help. Regards

 May 13, 2011, 02:00 #2 Member     Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 15 If you specify Mass Flow Fluent will calculate Pressure Gradient (see Fluent doc.)

 May 13, 2011, 02:32 #3 New Member   Ksaati Join Date: Oct 2010 Posts: 5 Rep Power: 14 Thanks for the reply. I referred the FLUENT manual specifying the translationally periodic boundary condition. I would like to know whether in Fluent the Periodicity associated with the periodic boundary condition could be found out my any methods? If i gave pressure gradient as 0 for translationally periodic condition is there any error?? Please help me to find this. I'm a beginner in CFD.It is extremely urgent!!

 May 13, 2011, 05:26 #4 Member     Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 15 With the periodic condition you compute the "fully-developed'' flow meaning infinite length (outlet=inlet) If you specify mass flow the value choose for the pressure gradient is the initial guess and will be update during calculation.

 May 13, 2011, 06:10 #5 New Member   Ksaati Join Date: Oct 2010 Posts: 5 Rep Power: 14 My problem is to get the periodicity associated with the boundary condition "periodic". Is there any option in FLUENT to calculate the periodicity associated with the boundary condition??

 May 13, 2011, 07:35 #6 Member     Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 15 What do you mean exactly by "periodicity" ?

 May 13, 2011, 11:31 #7 New Member   Ksaati Join Date: Oct 2010 Posts: 5 Rep Power: 14 Actually I need to know whether it is possible to find the period T associated with the boundary condition. Is there actually any period associated with the boundary condition " PERIODIC" as the name suggests ? Thanks in advance

 May 16, 2011, 03:59 #8 Member     Laurent B Join Date: Jun 2009 Location: Lille, FRANCE Posts: 70 Rep Power: 15 No, not any period is associated with the boundary condition " PERIODIC"