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How to set initial velocity in level-set method two phase flow for one phase

Posted Feb 27, 2013, 3:03 p.m. EST Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.3 4 Replies

Osameh Ghazian
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Hi guys,
I am trying to set the initial velocity for a droplet as fluid 1, how can I set an initial velocity for the bulk of fluid (for example the the continuous phase or the drop) in level set method?
I am trying to model the impact of the drop on the surface, I wanna increase the impact velocity.
4 Replies Last Post Mar 13, 2013, 9:57 p.m. EDT
Ryan McDevitt
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Posted: 1 decade ago Feb 27, 2013, 5:12 p.m. EST
You can add a second "Initial Values" node from the model tree. This allows you to select the domains containing the continuous phase, and assign a separate initial condition.
You can add a second "Initial Values" node from the model tree. This allows you to select the domains containing the continuous phase, and assign a separate initial condition.
Osameh Ghazian
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Posted: 1 decade ago Feb 27, 2013, 5:43 p.m. EST
thanks for your reply. But I think initial value is different from initial condition.
initial value could be anything just for the solver to initialize the problem. but initial condition means exact value at t=0.
there is no initial condition in COMSOL. I think we have to it manually.
thanks for your reply. But I think initial value is different from initial condition. initial value could be anything just for the solver to initialize the problem. but initial condition means exact value at t=0. there is no initial condition in COMSOL. I think we have to it manually.
Ryan McDevitt
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Posted: 1 decade ago Feb 27, 2013, 6:37 p.m. EST
"Initial Value" serves as an initial guess for a stationary solver or as an initial condition for a transient solver. For reference you can check page 526 of the User's Guide.
"Initial Value" serves as an initial guess for a stationary solver or as an initial condition for a transient solver. For reference you can check page 526 of the User's Guide.
Osameh Ghazian
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Posted: 1 decade ago Mar 13, 2013, 9:57 p.m. EDT
Thanks for you reply.
But if you change the initial value of velocity, it doesn't converge, because the phase initialization solver for level-set is very sensitive to this initialization. It is not even possible to use a time step function for velocity to gradually increase it, cause the phase initialization in not time dependent.
Any idea how we can set an initial velocity rather than zero for one of the phases in level set method?
Thanks for you reply. But if you change the initial value of velocity, it doesn't converge, because the phase initialization solver for level-set is very sensitive to this initialization. It is not even possible to use a time step function for velocity to gradually increase it, cause the phase initialization in not time dependent. Any idea how we can set an initial velocity rather than zero for one of the phases in level set method?

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