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Hi there,

I would like to know how to get the current profile for a specific location using the magnitude Velocity UV generated by Telemac2D. I know T2D outputs the depth-average, and I am not considering a 3D model, so looking for a way to estimate the current profile.

I searched for the power laws and they are based on the speed at the surface.

For example: V = V0 * (z/d)^1/7

where V0 is the speed at the surface
z is the distance above the seabed
d the depth


Is there a way to get the speed at the surface value, please? Maybe using BlueKenue?

Many thanks
MY

Your average water velocity is at 0.6 from the surface, where z/d=0.4 you know V from telemac and you can solve for V0.

V0=V/(0.4)^1/7

Hope that helps,

Patrick

Hi Patrick,

Thank you for coming back to me.

I am not sure I understand what you meant.

So, the equation I want to use to calculate the velocity profile V(z) is

V(z)= Vsurface * (d/h)^1/7

Not sure how you got the d/h=0.4. I am trying to solve for V(z) and want to find Vsurface

I would greatly appreciate it if you could elaborate more.

Many thanks

The mean velocity is at 0.4 from the bed. So you can calculate the surface velocity from that.

That is all

Hello,

To complete Patrick's answer, if you consider a theoretical profile with a power 1/7 law, V = Vsurf(z/d)^(1/7) with Vsurf the surface velocity and if you write Vm the average velocity over the vertical (the one computed by TELEMAC-2D), you can write:
Vm = 1/d int(0,d, Vsurf(z/d)^(1/7)dz = Vsurf/d [z^(8/7)/(8/7)/d^(1/7)] between 0 and d, = 7/8 Vsurf.

And if you try to solve V = Vm, you have to solve 7/8 = (z/d)^(1/7) which gives z = 0.39 (around 0.4).

Anyway, do not forget that it is a theoretical profile and surface velocity may differ (e.g. with the wind effect).

Chi-Tuan