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nitiniitp October 13, 2011 10:20

flow through a PIPE
I am simulating flow through a circular pipe embedded in a block of some dimension.The boundary conditions are:
Mass flow inlet : mass flux=362kg/m^2-s,Temp.=288.14K
Press outlet: default
Constant temperature boundary condition defined by UDF on the top and bottom wall of the block and rest 4 walls of the block are insulated.
I am using coupled boundary condition with zero heat generation for circular pipe wall.
The material of block is steel and fluid flowing in circular pipe is CO2 and properties are defined by UDF.
I have defined properties of both steel and CO2 seperately.Solver type is pressure based.

Turbulence model is EWF K-epsilon method and solution method is SIMPLE-pressure-velocity coupling and second order upwind for all equations.
When I am running the calculation its showing the error:
Error: Divergence detected in AMG solver: pressure correction
I have reduced the urf to considerable value but still its showing the error.I am using default values for solution initialization.
Please guide me how to proceed with the simulation and get rid of this error.

Thanks in advance..

m2montazari October 13, 2011 16:01

I dont know your dimensions, but your desired mass flow rate is extremely high!! recheck and ensure that is right. then initialize with this boundary or simply set a velocity equal to mass flow rate divided by section area of pipe. with UR about 0.1 start the solution and after some iterations use higher values for UR. you can use simplec for better performance if your grid quality is good.
as a PS., did you checked the scale of geometry?

nitiniitp October 14, 2011 00:40

The dimensions I've been using for the block are 500mm x 69.85mm x 25.4mm. The channel diameter is 6.35mm (1/4") and it goes the length of the block (500mm).

362kg/m^2-s is the mass flux flow rate and not the mass flow rate.


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