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VOF for single phase?

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Old   April 20, 2011, 19:59
Default VOF for single phase?
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This post is lengthy- with hopes that it is as complete and thorough as possible. Please bear with me and thank you in advance.

My experience with FLUENT has been pretty one-dimensional (though not in the geometrical sense). My modeling is simply steady-state applications of flow perfusion throughout various devices/designs...basic velocity inlets, pressure outlets, and occasional porous media domains.

But now I have a need to visualize the time-dependent progression of the 3D volumetric flow through my devices. I need to be able to define various 2D planes (at different perspectives/orientations) and look at the fluid as it fills the cavity in a discrete fashion. I can step through the fluid flow using DPM particle injections, but this only shows pathlines- and adding rakes/surfaces to the inlet still is limited by the grid resolution of my mesh. Not to mention I haven't found a way to view pathlines of a 3D model on an 2D surface...

Any thoughts on how to visualize the data I have in the fashion described above without the need of any discrete/multiphase modeling?


I tried a VOF model, with phase 1 and 2 as the same liquid (logic being that phase 2 replaces phase 1) but am having difficulties with BCs (possibly errors due to patching?) and post-processing. The parameters in my model are:


-Pressure-based, unsteady solver
-Implicit, 2-phase (identical material properties) VOF
-BCs: Inlet: phase 2 volume fraction = 1; mixture = absolute [constant] velocity
Outlet: phase 2 volume fraction = 0; mixture = pressure outlet
-PISO P-V coupling
-Discretization: Green-Gauss Node Based, PRESTO!, momentum and volume fraction are both Second Order Upwind
-Second Order Implicit Transient Formulation
-Non-Iterative Time Advancement is turned OFF
-Default under-relaxation factors
-(no surface or volume monitors are created - should they??)
-Initialization: phase2 volume fraction has been set at both 0 and 1 (neither yield usable data)
-(I could not patch any surfaces as was done in the FLUENT tutorial. Some other forum posts said this could be done with the same scheme employed in an adaptive mesh- but I don't want to have an adaptive mesh - any work-around??)
-Fixed time step size of 1e-5, 2000 time steps, 20 iterations/time step, report interval = 1

Misc.: laminar, incompressible fluid


Results are not consistent with steady-state data (though the solver says convergence is met (1e-4)). NOTE: steady-state data has been validated and presumed accurate.

Moreover, I cannot define discrete time points in my contours [viz. contours-> phases -> phase # -> volume fraction]. All graphs are at time == 0 and phase 1 = uniformly 1, phase 2 = uniformly 0. I can't define vf = .5 (e.g.).

I know this was lengthy, but hopefully it was thorough enough to assist the reader in their support. Thank you kindly.
vuccj7 is offline   Reply With Quote


boundary conditions, filling, steady, transient, vof

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