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-   -   how simulating a water-particle current into sea (http://www.cfd-online.com/Forums/fluent/92984-how-simulating-water-particle-current-into-sea.html)

doronzo September 30, 2011 14:52

how simulating a water-particle current into sea
 
Hi

I have to simulate a water-particle flow entering laterally a body of water, i.e. sea or lake. The flow is already subaqueous at the beginning, so it should enter a sea which is stratified for static pressure (1 atm/10m_down).

Do I need to activate the gravity field only, so that the operating pressure I choose (1 atm as reference at free sea level) is automatically increased with depth? What happens at the initial instant? I need to have a static sea, where everything is 0 at t=0, and then the flow enters laterally (a sort of tsunami, or push of water), by starting to mix with the initial sea.

Once the flow enters (5 m/s for water 60 m thick, and for 3% of 3_grain-size Lagrangian particles), it rapidly expands upward, it seems to have no inertia, it is not able to move laterally, at least at the beginning, and the particles follow that upward flow.

Are the two things related? May be the entering flow doesn't find physically what I want to simulate (a static pressure-stratified still sea)?? I tried to change everything (time step, discretization order, operating pressure, operating density), but anything happens. May be is it the real solution, because the still water generates a high resistance so the flow moves rapidly to a wake region? The inflow has homogeneous velocity with depth, and this effect happens mainly on top (higher resistance of still water?)

Many thanks


Domenico


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