[EJohn]

Hey all,

I have a 5m cylindrical pipe submerged vertically in a tank which has a height of 5m and length of 20 m horizontally. The inlet has water flowing in at 10m/s and exiting to atmosphere.

I am interested in modelling the hydrostatic pressure distribution with depth since this would be significant towards the bottom of the pipe. I have looked though threads on this site but couldn't find sufficient information to correctly simulate my case.

Since simpleFoam doesn't model gravity, one can make corrections to the momentum equation by adding 'g'. I am not sure if this is a suitable approach but I was thinking if it would be possible to use certain boundary patches on the inlet or outlet to account for a non-uniform pressure gradient.

buoyantBoussinesqSimpleFoam is also recommended for these cases. But after testing it out I found that there is no difference in the pressure gradient of the p_rgh data fields even after increasing the acceleration from 9.81 to 20 m/s^2.

I would really appreciate it if someone can provide some insight to my problem.

Thanks,
Edward

[EJohn]

Any useful feedback is appreciated.

Thanks,
Edward

[arvindpj]

Originally Posted by EJohn

Hey all,

I have a 5m cylindrical pipe submerged vertically in a tank which has a height of 5m and length of 20 m horizontally. The inlet has water flowing in at 10m/s and exiting to atmosphere.

I am interested in modelling the hydrostatic pressure distribution with depth since this would be significant towards the bottom of the pipe. I have looked though threads on this site but couldn't find sufficient information to correctly simulate my case.

Since simpleFoam doesn't model gravity, one can make corrections to the momentum equation by adding 'g'. I am not sure if this is a suitable approach but I was thinking if it would be possible to use certain boundary patches on the inlet or outlet to account for a non-uniform pressure gradient.

buoyantBoussinesqSimpleFoam is also recommended for these cases. But after testing it out I found that there is no difference in the pressure gradient of the p_rgh data fields even after increasing the acceleration from 9.81 to 20 m/s^2.

I would really appreciate it if someone can provide some insight to my problem.

Thanks,
Edward

Yes, if the density dependence of temperature is low to moderate, i.e., for fluids like water at STP, you can use buoyantBoussinesqSimpleFoam

In buoyantBoussinesqSimpleFoam , the field variable name 'p_rhg' mean the pressure field is subtracted by the hydrodynamic component (rho.g.h) thats why you are not seeing the pressure gradient. In order to see the pressure gradient, see the 'p' field.

Cheers,
Jay

[EJohn]

Originally Posted by arvindpj

Yes, if the density dependence of temperature is low to moderate, i.e., for fluids like water at STP, you can use buoyantBoussinesqSimpleFoam

In buoyantBoussinesqSimpleFoam , the field variable name 'p_rhg' mean the pressure field is subtracted by the hydrodynamic component (rho.g.h) thats why you are not seeing the pressure gradient. In order to see the pressure gradient, see the 'p' field.

Cheers,
Jay

Hi Jay,

Thanks for your reply.

I noticed that the 'p' field shows only the static pressure. Would it be possible to combine the dynamic and hydrostatic pressures so that I can see the total pressure field?

Regards,
Edward

[arvindpj]

Originally Posted by EJohn

Hi Jay,

Thanks for your reply.

I noticed that the 'p' field shows only the static pressure. Would it be possible to combine the dynamic and hydrostatic pressures so that I can see the total pressure field?

Regards,
Edward

'p' field does include the hydrostatic component when you use buoyant solvers and have gravity on.

If you still need total pressure, which also include the 0.5*rho*u2 component you can use the totalPressure postprocess utility.

-Jay

[Mahmoud Abbaszadeh]

Originally Posted by EJohn

Hey all,

I have a 5m cylindrical pipe submerged vertically in a tank which has a height of 5m and length of 20 m horizontally. The inlet has water flowing in at 10m/s and exiting to atmosphere.

I am interested in modelling the hydrostatic pressure distribution with depth since this would be significant towards the bottom of the pipe. I have looked though threads on this site but couldn't find sufficient information to correctly simulate my case.

Since simpleFoam doesn't model gravity, one can make corrections to the momentum equation by adding 'g'. I am not sure if this is a suitable approach but I was thinking if it would be possible to use certain boundary patches on the inlet or outlet to account for a non-uniform pressure gradient.

buoyantBoussinesqSimpleFoam is also recommended for these cases. But after testing it out I found that there is no difference in the pressure gradient of the p_rgh data fields even after increasing the acceleration from 9.81 to 20 m/s^2.

I would really appreciate it if someone can provide some insight to my problem.

Thanks,
Edward

Hi Ed,

Have you found an answer to your question? I want to define the hydrostatic pressure with the simpleFoam. It seems that there is no such an option