I'm simulating collision of a droplet and a moving particle in mid-air. The particle is launched towards the droplet while the drop is moving in opposite direction (pls. see Fig. 1)
For solving this problem, I need to know how to assign an initial velocity to a moving wall (particle).
So far I've tried the following methods:
1) I used C.o.G. velocity in Dyn.Mesh.Zone window => But it's not an initial value and I believe keeps the velocity constant
2) I used DEFINE_INIT in a udf => But I think it only works for fluids as you need to determine the cells that velocity should be patched to.
What I need to assign to the particle is just initial vel. and so all velocities after t=0 will be calculated step by step based on air drag, interfacial forces with droplet, etc.
Any hints on how to doing that is appreciated!
There are two ways to do that in fluent, but I recommend you to define the domain as a moving frame, with translational velocity as a reference velocity for the moving solid. If you do this, your problem is far less complex.
The other way is to attribute the wall as non-stationary and moving with the specific velocity and use the dynamic mesh, but it could be more dificult to simulate it and considerably spend more time for processing it.
Agree with Guilherme. If in your case is possible, apply a moving reference frame. Obviously you can get just the regome condition; the transitory is only numerical and without phisical meaning. Otherwise move the boundaries with an UDF and use mesh smoothing/remeshing.
Franco
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