Lock-Exchange flow with free surface

Tasos · July 20, 2015, 13:32

Hallo everyone,

I want to simulate the Lock-Exchange flow with free surface, but i am not sure which solver should i choose. I have got two fluids (salt water and fresh water) and because i have free surface i also have the air. So i have to make a simulation with 3 fluids. I am between the interMixingFoam, the multiphaseInterFoam and the multiphaseEulerFoam. So what is your opinion? What should i choose and why?

Thanks in advance,
Tasos

vonboett · November 11, 2015, 04:12

the multiphaseInterFoam is working best for immiscible phases, don't use that. InterMixingFoam is about 10 x faster than multiphaseEulerFoam but you will not get much momentum exchange between the miscible phases and itz has some drawbacks by the trade-off between keeping concentrations bound between 0 and 1 and conserving mass. It solves for the immiscible phase (air) and one of the miscible ones but in your case your focus is probably more on the salt than on the air. Thus it would make sense to rewrite it to solve the scalar transport equations for the two miscible phases and get the air phase as 1.0 - alpha.freshwater - alpha.saltwater. MultiphaseEulerFoam is quite well but maybe not necessary if you are only interested in diffusion. I think it solves the Navier-stokes equations for each phase and exchanges momentum via drag so that might bring additional parameters that take time to calibrate, but I am not so familiar with it so don't trust me here.

July 20, 2015, 13:32	Lock-Exchange flow with free surface	#1
Tasos New Member Anastasios Stampoultzoglou Join Date: May 2014 Posts: 21 Rep Power: 11	Hallo everyone, I want to simulate the Lock-Exchange flow with free surface, but i am not sure which solver should i choose. I have got two fluids (salt water and fresh water) and because i have free surface i also have the air. So i have to make a simulation with 3 fluids. I am between the interMixingFoam, the multiphaseInterFoam and the multiphaseEulerFoam. So what is your opinion? What should i choose and why? Thanks in advance, Tasos

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November 11, 2015, 04:12		#2
vonboett Senior Member Albrecht vBoetticher Join Date: Aug 2010 Location: Zürich, Swizerland Posts: 237 Rep Power: 16	the multiphaseInterFoam is working best for immiscible phases, don't use that. InterMixingFoam is about 10 x faster than multiphaseEulerFoam but you will not get much momentum exchange between the miscible phases and itz has some drawbacks by the trade-off between keeping concentrations bound between 0 and 1 and conserving mass. It solves for the immiscible phase (air) and one of the miscible ones but in your case your focus is probably more on the salt than on the air. Thus it would make sense to rewrite it to solve the scalar transport equations for the two miscible phases and get the air phase as 1.0 - alpha.freshwater - alpha.saltwater. MultiphaseEulerFoam is quite well but maybe not necessary if you are only interested in diffusion. I think it solves the Navier-stokes equations for each phase and exchanges momentum via drag so that might bring additional parameters that take time to calibrate, but I am not so familiar with it so don't trust me here.