Reinolds number in sola-vof.

JSS · October 21, 2009, 02:47

hello, friends!
sorry for stupid question.
Please, help! How I can define Reinolds in program (for example sola-vof)? for simulating some process with others Re.
Please explain the issue with the dimensions. How to set the dimension of the variables in the program?
thank you!

otd · October 21, 2009, 10:12

Most of the Los Alamos codes written at the time of Sola-Vof (~ 1980) allow any consistent set of units to be used. There are no units specified for the examples in the LANL report documenting the original code.

That is, the body forces g_x and g_y, the velocities (u and v), the viscosity, the density rho, the surface tension (for free surface simulation) and the mesh units (x, dx, y, dy, etc) must all be consistent. You can use cgs, MKS, English units (pounds_m, feet, seconds), etc. Or non-dimensionalize the equations, which will form dimensionless quantities (Reynolds number, etc). You should find help in engineering texts for heat transfer or fluid dynamics - subtitles might be "dimensional analysis" or "Buckingham's Pi Theorem."

This should all be worked out before you start inputting to the code.

JSS · October 21, 2009, 13:15

Quote:

Originally Posted by otd

This should all be worked out before you start inputting to the code.

Thank you!
One last question: how can define сircle on grid in VOF method?
I tried to manually fill the fluid cell, but I could't configure cells at the boundary of the circle. And I think, that my "method" is wrong.
May be by some equation possible to specify a this configuration for F?

otd · October 21, 2009, 14:17

Sorry but I don't really have much experience with the VOF option. Only things I've used it for are simple surfaces that initially coencide with cell boundaries.

October 21, 2009, 02:47	Reinolds number in sola-vof.	#1
JSS New Member Jas Join Date: Sep 2009 Posts: 4 Rep Power: 16	hello, friends! sorry for stupid question. Please, help! How I can define Reinolds in program (for example sola-vof)? for simulating some process with others Re. Please explain the issue with the dimensions. How to set the dimension of the variables in the program? thank you!

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October 21, 2009, 10:12		#2
otd Member private Join Date: Mar 2009 Posts: 74 Rep Power: 17	Most of the Los Alamos codes written at the time of Sola-Vof (~ 1980) allow any consistent set of units to be used. There are no units specified for the examples in the LANL report documenting the original code. That is, the body forces g_x and g_y, the velocities (u and v), the viscosity, the density rho, the surface tension (for free surface simulation) and the mesh units (x, dx, y, dy, etc) must all be consistent. You can use cgs, MKS, English units (pounds_m, feet, seconds), etc. Or non-dimensionalize the equations, which will form dimensionless quantities (Reynolds number, etc). You should find help in engineering texts for heat transfer or fluid dynamics - subtitles might be "dimensional analysis" or "Buckingham's Pi Theorem." This should all be worked out before you start inputting to the code.

October 21, 2009, 14:17		#4
otd Member private Join Date: Mar 2009 Posts: 74 Rep Power: 17	Sorry but I don't really have much experience with the VOF option. Only things I've used it for are simple surfaces that initially coencide with cell boundaries.