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-   -   dilute gravity current at very flow base (http://www.cfd-online.com/Forums/fluent/93123-dilute-gravity-current-very-flow-base.html)

doronzo October 5, 2011 15:38

dilute gravity current at very flow base
 
Hi

In a dilute turbulent current, the flow structure is mainly described by the logarithmic region in the lower part, and the Gaussian wake region in the upper part. The two profiles of velocity depend on resistance effects at contact with wall, and surrounding fluid, respectively.

Let's consider such a current, meters thick, depositing a thin layer of particles through its more concentrated base (current is velocity- and concentration-stratified) as it moves. Let's call the very basal part of the current emplacing that layer as ''undeflow''. The resulting deposit is 1 cm thick, so the parent undeflow from which is generated is probably about few cm, which means that is not dilute as the total current (on average).

I need to extend, as an approximation in a theoretical model, the logarithmic region, which describes well the turbulent region above the underflow, to the underflow itself. Do you think this is an heresy, or there is something to support the approximation, i.e. reference, experiment, etc...? Let's keep in mind the scale of the system, which is of a current meter to tens of meters thick emplacing a layer 1 cm thick (could that underflow be indulgent to turbulence? :)

Many**2 thanks. Regards


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