[keepfit]

Hi Foamers,

I want to simulate free surface flow (or stream flow) around cylinder. Now RAS model SST k-omega is used.



[v=2m/s at +x direction, the water level is set to h=0.6m using groovyBC]


It seems that the results looks reasonable (see Fig above), however, the hydraulic jump at the front of Cylinder looks weird, while the flow is more or less "dynamically stable". Is it because the inlet is too close to the Obstacle - cylinder?



I checked the BCs but could not figure this out, is there some wrong the BCs with inlet?

Best

David

[Phicau]

Hi David,

you are specifying 2 conditions for the flow: level and velocity.

Your level is increasing due to the presence of the obstacle, but GroovyBC does not allow the flow to reach the boundary (see how there is no water above your given level for the cells adjacent to the inlet).

Depending on what was your goal, taking the inlet far away enough from the cylinder may solve your problem, if you want to prescribe both level and velocity.

If what you need to impose is only a discharge (velocity) I guess you should leave alpha1 as zeroGradient and code a BC to calculate the wet area and apply the calculated velocity to such area. In this case you most probably can reach a stable state with your current domain.

Best,

Pablo

[keepfit]

Originally Posted by Phicau

Hi David,

you are specifying 2 conditions for the flow: level and velocity.

Your level is increasing due to the presence of the obstacle, but GroovyBC does not allow the flow to reach the boundary (see how there is no water above your given level for the cells adjacent to the inlet).

Depending on what was your goal, taking the inlet far away enough from the cylinder may solve your problem, if you want to prescribe both level and velocity.

If what you need to impose is only a discharge (velocity) I guess you should leave alpha1 as zeroGradient and code a BC to calculate the wet area and apply the calculated velocity to such area. In this case you most probably can reach a stable state with your current domain.

Best,

Pablo

thanks for your tips.

the inlet velocity is set quite low while keep the water level, now the result is fine!

Btw, how to set the outlet BCs to achieve the same water level as inlet's?

best,

David