Kappa is defined as the ratio of (k=l/y), l is mixing length and y is the vertical distance in the flow filed. What does it means? How does the variation in k affect the turbulent velocity profile or turbulent characteristics and what are their physical significance in turbulent flow analysis?
Virtual Bed level (dz) or Reference bed level has got much importance in literature but what does virtual bed level in fluvial hydraulics exactly means?
Computation of the k and dz from the procedure described by Dey et al. 2012, I am getting highest regression coefficient when dz is negative. It indicates virtual bed level is above actual bed, which is physically unjustifiable. What could be the probable reasons for that?
Hello.
As you said, the von Karman constant is the ratio between two lengths. It allows you to determine the mixing length from the wall-distance. It is also related to the slope of the log-law.
I do not know the paper that you mention (Dey et al. 2012), but I know that the virtual bed level can be seen as the centroid of the drag force.
Kappa is adimentional function then may define several ratios. Taken as function of U (velocity) and S (Slope in square root of U*) it behaves as a "State function" whereas it follows Schwatrz condition. The function value 0.382 has a special meanning because the longitudinal spreading of tracer is complete.
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