Depending on the Re number values.

" When I calculate rms value it will give only one value. "

What do you mean?

Filippo Maria Denaro

Thank you for your reply. I meant that root mean square (rms) is root over of average of fluctuations velocity. It will give a single value. If I divide this by mean velocity it will give turbulence intensity. But I need turbulence intensity value for each depth like as depth aver velocity.

V = rms (2 g h)

Arif Jewel

The fluctuation of a velocity component uj' is a function of (x,t), when you apply an averaging operator to the product of fluctuations it is still a function of x. How can you get a single value??

Filippo Maria Denaro

Thank you for your answer. I have understood your point that the fluctuating velocity component is a function of (x,t). When I apply time averaging operator, it will produce function of x only. But I collected data as variation of flow depth. I am not understanding variable t here.

For your convenient I am attaching here the calculation file.

If you don't mind, could you please tell me how to proceed for turbulent intensity from this point.

You cannot do the average along the depth...

@Filippo Maria Denaro

So you mean I can not calculate turbulence intensity from the present data

If you want to compute the rms profile along the depth you need to perform the spatial average of the fluctuations product over the horizontal plane at each depth value. This way the rms is a function only of the depth. Have you the data in the horizontal planes?

Filippo Maria Denaro

Thank you for your answer. PIV was used to collect side view images of the experimental flume. I extracted streamwise (x) component of velocity along the depth. I can also extract vertical (y) component of velocity from the image collected using PIV. But I am not understanding data in the horizontal planes.

Could you please tell me in detail?

Arif Jewel

if z is the depth direction, the horizontale plane is (x,y). At each station z you should perform the average in x and y. But if you do not have such data your rms are not statistically valid.

Filippo Maria Denaro

Thank you for your kind reply.

I have the velocity components in x and y directions which is attached here for your convenient. Could you please help me to calculate rms profile from this data?

Arif Jewel

you are not understanding the issue. You need to know the velocity components also in points over the horizontal plane, not only along the depth. Your file has only u and v along y/d

Filippo Maria Denaro

Thank you so much for your active conversation.