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Deformation of a water droplet in a cilindric pipe with a toluene flow
Posted Mar 16, 2015, 8:13 a.m. EDT Fluid & Heat, Microfluidics, Mesh, Studies & Solvers 0 Replies
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I'm new in Comsol and I'm trying to solve a problem for an exam. I have a droplet of water placed on the axis of a cilindric pipe, and in the pipe flows toluene. I have to evaluate the deformation with different pressure drops, or imposing different value of the velocity of the toluene.
I have used the following settings:
- model two phase flow, level set
- model 2D axysimmetric
- diameter of the droplet 4 mm
- diameter of the pipe= 30*diameter of the droplet
Here the problems that I found. My professor says that I should observe the deformation in an "infinite pipe" meaning that when the drop leaves the pipe , it should reenter from the bottom and rise up again while the toluene is flowing. And this will go on until the time reaches the final value of the solver ( I have setted range(0, 0.5, 20)). He said that I should impose periodic flow condition for the inlet and outlet boundary, but if I do this the droplet in time does not move, remains on its position and reduce progressively its volume.
Second way: I have applied for inlet a condition of fully developed flow (parabolic), for the outlet Pressure no viscous stress. In this case the professor says that I can observe the droplet while it is moving imposing a condition of moving or sliding wall, to the lateral wall of the pipe. But if I do that the droplet leaves anyway the pipe, let's say that "I can't move with an immaginary camera and follow the drop while it is moving". I don't know if my explanation was good.
Any suggestion about I could solve this problem?
Last problem: the volume of the droplet decreases progressively during the simulation, and the interface of the droplet tends to disappear while the droplet is supposed to assume a stationary shape after some times that the toluene flows . I have setted the reinitiaization parameter to the half value of the maximum velocity in the pipe and the mesh is extra fine free triangular on the interface. The convective term in the model is on "non coservative form", the "conservative" form takes really long to be solved and I had to stop the simulation.
If there is someone that has solved these kinds of problems or that have some suggestion, a little help would be very appreciated. Thanks!
Hello Leonardo De Stasio
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