[jignesh_thaker2007]

i am trying to solve the two phase simulation of hose pipe which is located at sea so its shape becomes like wave. and continuously water and air are flow inside the one end of the pipe and the other hand is fixed.
pipe is moving like wave so when the inlet end of the pipe is going above then air is come inside the pipe and when it comes down then water come inside the pipe.
i got the simulation of moving mesh and also got the simulation of air and water inside the pipe with interDyMFoam. but it is for same velocity of air and water.
But now i have trouble in how to give the different velocity of air and water? so plz help me.
i m still waiting for ur reply.
thank you very much.

[Nilesh_87]

Hello Sir,
I am solving 2D external aerodynamic case of simple ahmed car profile. I am using pisoFoam. deltat is 0.001. but i am getting very high courant number. I assumed Co. no. as 1 and fixed deltat. Can you please help me?

Thanks & regards
Nilesh

[jignesh_thaker2007]

Originally Posted by Nilesh_87

Hello Sir,
I am solving 2D external aerodynamic case of simple ahmed car profile. I am using pisoFoam. deltat is 0.001. but i am getting very high courant number. I assumed Co. no. as 1 and fixed deltat. Can you please help me?

Thanks & regards
Nilesh

i am happy to see that you are using openFOAM. now for your problem first u see the openFoam tutorials of lid driven cavity in that tutorial u will find your answer because in that u will find the courant number condition and its definition,

if u unable to find that then replied me ok
best wishes

Jignesh

[musahossein]

Originally Posted by Nilesh_87

Hello Sir,
I am solving 2D external aerodynamic case of simple ahmed car profile. I am using pisoFoam. deltat is 0.001. but i am getting very high courant number. I assumed Co. no. as 1 and fixed deltat. Can you please help me?

Thanks & regards
Nilesh

Courant number of 1 is very high, and can lead to instability when you have fine mesh or your computations require many iterations. As suggested in another post, please review the lid driven cavity example and try with the courant number there. Once you have decided on a Courant number you can determine the appropriate deltaT based on your cell size. This is also explained in the referenced example.

[zijun]

Hi Guru Foamers,

Will the above discussed approach work too is 'LTSInterFoam' solver is used (if main interest is on the free surface)?

Thanks

[musahossein]

I would suggest that you look at the example for ltsinterfoam and determine the appropriate courant number. I have not used this solver. The example can be found at:

$FOAM_TUTORIALS/multiphase/LTSInterFoam/wigleyHul

As far as I know, the solver uses local courant number. However what that number actually is, you will need to find from the example.

[zijun]

Dear Musahossein,

Thanks for your reply.

I used this tutorial and obtained nice Kelvin wave pattern on free surface.

However, I was thinking whether it is possible to use this solver to:

1. include the wind effect too, to simulate the wind generated ripples on free surface.
2. to include incoming wave (as there is sea state or something)

Another concern is how to avoid boundary reflection if the simulation running for very long time or much more steps than the tutorial setting.

Thought the previous discussion might be related to my doubts, any one can advise?

Thanks a lot!


zijun

[pltw]

Originally Posted by ngj

Hi Pierre,

One more consideration with respect to the problem you describe. The solver 'interFoam' produces considerable velocities in the air, which originate from numerical inaccuracies, so you should be very careful, if you are thinking of using interFoam to study the effect of wind on the shape and other properties of surface water waves.

Good luck,

Niels

Hi Niels,
Firstly, thankyou for producing your excellent wave modelling package.
I am fairly new to CFD, and am trying to study wind wave /wind current interaction. If InterFOAM is a poor option, do you know of any other solver / package that is suited to wind wave interaction?
Regards,
Peter