Introduction to Turbulence & Turbulence Modeling

[abdul.qayyum]

Everything is really well presented. However, we should be careful in stating that Turbulence reduces drag. Turbulence does not reduce drag. On a given surface area/length laminar flow always has less drag than turbulent flow. This sort of friction is called skin friction. The friction that happens when a flow wets the surface flowing. However for blunt bodies like a sphere, the flow separates at the equator causing "dead water" effect at the back of the back. When a flow separates, this creates a higher drag than laminar or turbulent flow, known as the pressure drag (form drag). This form drag is very high and most of the time it's greater than skin friction. What dimples in the golf ball does is that it energizes the boundary layer and flow stays attached for a greater distance on the surface. This flow attachment reduces flow separation, hence reduces form drag which in turn reduces the overall drag. It needs mentioning that in a situation where a flow does not separate (airfoil at low angle of attack), turbulent flows will increase the drag compared to laminar flow.

[manishvasavi]

Now I am clear with how Reynolds stress is related to turbulence modelling with your Expalnation...!!!
looking forward for more lectures from you..Sir
Thank you...:)

[kumargourabdas]

Turbulence explained in a laminar way .. thanks

[Obniaa]

Great explanation of difficult concept! Thanks buddy!

[RamaChandra-sojx]

I enjoyed all your lecture series. I am also fan of your accent. looking forward for more lectures from you.

[ayushmaansnurseryrhymes]

Finest presentation. The pictorial explanation is really good.

[mislavbosnjak]

Excellent intro to this certain theme.

[TehMaxLightning]

Damn this was super clear. Great examples/explanations.

[youhannaeylia]

Very good efforts. It will be better with improving your English accent :)

[mehrnoushkohandel]

We know interia is a resisting force, how can it be responsible for accelerating an object and how can it increase the velocity?

[harikrishnangp]

Malayali aano?? Ascent seems to be so. 😊

[sagar]

Please make physical meaning of NS equations and divergence physical meaning video too. Thanks for such superb explaination.

[sankrishjayachandran]

I have heard the voice but i am not able to recognize the preson

[AbhishekPatel-iknv]

i guss terbulance happens because after some laminar flow fluid has less energy, it gets nervous gets out of control, turning into randomness 

[atillaus]

effect of turbulence reduces drag ??? it is a wrong claim. just in special cases, turbulence can reduce wake regiıon hence drag

[satwikpriyadarshi]

Yes It is. Actually you can win Millennium Prize in Mathematics from CMI, Mass (USA) by solving it.
And most probably Nobel Prize and a few other honers will add a few more millions to your :-)

[itswhoppertime]

boopity beep! beep! Beep! bopity !! durka durka stan

[omarhaidar]

couldn't you find somebody else with a good English language????