[sa har]

hello,i try to simulate a solar air heater in ansys fluent.i have a channel that air entered of bottom and go out of up by natural convection.
boundary condition is:inlet(pressure inlet),outlet(pressure outlet)[both inlet and outlet pressure are 0],and boussinesq model for natural convection.
when i run,i have reverse flow that it disappeared after 1000 iterations. when run finished my pressure increases and counter of pressure is wrong,can you help me?
is operating pressure important?what means of operating pressure?

[ghorbani1992]

I think change your pressure solution method to PRESTO!
what is your turbulence model?

[sa har]

Originally Posted by ghorbani1992

I think change your pressure solution method to PRESTO!
what is your turbulence model?

hi amir,
i used standard-k-epsilon for turbulance model.and i used standard method for solve pressure.
when air move up,velocity should be increase and pressure decrease?is right?
thanks alot

[ghorbani1992]

Originally Posted by sa har

hi amir,
i used standard-k-epsilon for turbulance model.and i used standard method for solve pressure.
when air move up,velocity should be increase and pressure decrease?is right?
thanks alot

hi sahar
whenever change flow rate or cross section the velocity must be increase or decrease . but pressure must be decrease.
if in your problem , natural convection ( buoyancy force ) due to air flows , don't forget insert gravity.
I think that you have a correct simulation.

[sa har]

Originally Posted by ghorbani1992

hi sahar
whenever change flow rate or cross section the velocity must be increase or decrease . but pressure must be decrease.
if in your problem , natural convection ( buoyancy force ) due to air flows , don't forget insert gravity.
I think that you have a correct simulation.

yes,i insert gravity and i use bussinesq model.but my pressure increase when air move up.i think its maybe wrong.yes?

[ghorbani1992]

Originally Posted by sa har

yes,i insert gravity and i use bussinesq model.but my pressure increase when air move up.i think its maybe wrong.yes?

i thing that's wrong. change model to ideal gas ( for High temperature range recommend use boussinesq model).
If you can explain the problem in detail, may be i can describe it in more detail.

[sa har]

Originally Posted by ghorbani1992

i thing that's wrong. change model to ideal gas ( for High temperature range recommend use boussinesq model).
If you can explain the problem in detail, may be i can describe it in more detail.

i have channel that inlet is down and outlet is up,and left of channel is glass and right of channel is absorber.geometry is 3D.and i insert source term in absorber because of solar irratiton.glass wall boundray is mixed of convection and radiation,and other wall is heat flux=0.inlet is pressure inlet and temp is 320K and outlet is pressure outlet.and i active radiation DO model or S2S model.i want velocity in outlet
now i want test ideal gas instead of boussinesq model.
thanks alot