Level set Courant number

Numerical methods and mathematical models of Elmer
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Andrea_P
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Level set Courant number

Post by Andrea_P »

How Can I compute the Courant number for the level set? Probably my question is trivial. I know that the Delta_x(grid dimension), Delta_t (time step) and velocity V appear in the Courant number, but what is that V? How can I compute in a simulation?
Regards,
Andrea
POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
annier
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Re: Level set Courant number

Post by annier »

Dear Andrea,
You have to define the Courant number (less than or equal to 1) yourself in the simulation section of the sif file.
If you do not define it there, the default value of Courant number = 1 is utilized in the simulation.
Last edited by annier on 04 Sep 2021, 17:14, edited 1 time in total.
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
annier
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Re: Level set Courant number

Post by annier »

Andrea_P wrote: 03 Aug 2021, 13:28 How Can I compute the Courant number for the level set? Probably my question is trivial. I know that the Delta_x(grid dimension), Delta_t (time step) and velocity V appear in the Courant number, but what is that V? How can I compute in a simulation?
Regards,
Andrea
The V in Courant number (C) = V* (Delta_t/Delta_x) is the advection velocity of the level set equation. It is the advection velocity u in Eq. 32.1 ( level set equation) of https://www.nic.funet.fi/index/elmer/do ... Manual.pdf It is provided as an input (LevelSet Velocity i) in the Materials block of Elmer's solver input file. For level set equation coupled with navier-stokes equation it (level set velocity) is defined by the velocity varibales of flow equation at the interface; and this relationship must be established at the materials block.
For simulations using level set equation, it is always a good idea to use a smaller timestep.
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Andrea_P
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Joined: 22 Mar 2021, 18:39
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Location: POLYTHECNIC UNIVERSITY OF TURIN

Re: Level set Courant number

Post by Andrea_P »

annier wrote: 04 Sep 2021, 17:10
Andrea_P wrote: 03 Aug 2021, 13:28 How Can I compute the Courant number for the level set? Probably my question is trivial. I know that the Delta_x(grid dimension), Delta_t (time step) and velocity V appear in the Courant number, but what is that V? How can I compute in a simulation?
Regards,
Andrea
The V in Courant number (C) = V* (Delta_t/Delta_x) is the advection velocity of the level set equation. It is the advection velocity u in Eq. 32.1 ( level set equation) of https://www.nic.funet.fi/index/elmer/do ... Manual.pdf It is provided as an input (LevelSet Velocity i) in the Materials block of Elmer's solver input file. For level set equation coupled with navier-stokes equation it (level set velocity) is defined by the velocity varibales of flow equation at the interface; and this relationship must be established at the materials block.
For simulations using level set equation, it is always a good idea to use a smaller timestep.
Dear annier,
Thanks for your precious help, it was a confirmation of my suposition.
Regards,
Andrea
POLYTECHNIC UNIVERSITY OF TURIN-DIMEAS
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