Non-dimensional numbers [Fluid Mechanics #5]

[@manishankaryadav7307]

Thank you for the quality content, hard work and humor.

[@prof.vanburen]

Thanks for the kind words!

[@olimolim7230]

I'm unable to go to my university because of the earth quake in turkey. It has been so long since i enjoyled learning so much. Thank you!

[@prof.vanburen]

Oh goodness I hope all is okay! What a tragedy that has been. Glad you are liking the videos.

[@이사야-x9s]

8:55 how could we consider (delta u) and (delta y) can be changed to reference u and y respectively, unlike (delta p) in Euler Number? We didn't change (delta p) to reference P in this case.

[@prof.vanburen]

Great question! It's more convention than anything, and for the Reynolds numbers often the velocity scales and length scales change. However, we can change the (delta u) and (delta y) to a (u) and a (y) because often the starting reference point is a surface where y = 0 and U = 0, so very crudely (delta U) = U - 0 and (delta y) = y - 0. However, this is not always the case for pressure. Unfortunately, fluid mechanics/aerodynamics in general is riddled with lingering conventions that we try to mash together, and often you have to have in-depth knowledge of the problem to set it up properly.

[@이사야-x9s]

@@prof.vanburen Thank you for your answer. Your video is so helpful!

[@yempadayugesh8195]

in almost all non dimensional numbers the velocity is maintained at power 1 so that why the number are either taken square root or not

[@prof.vanburen]

Ah I see, though the Euler (and every subsequent aerodynamic coefficient like drag, lift, moment, etc) all stay with power 2.