Viscous Drag

infikamal5 · January 9, 2015, 08:47

Hi,

I would to know if the viscous drag coefficient and the skin friction drag coefficient are the same ??

Thanks

t.teschner · January 9, 2015, 10:34

Yes (at least I have not heard of a different definition). Viscous drag is caused by boundary layers and hence is the same as skin friction.

I think you have the two terms as in aerodynamics you distinguish between a lot of different forms of drag (total drag, induced drag, zero drag, wave drag, interference drag, profile drag, misc drag, pressure drag and skin friction) so here, the profile drag of an airfoil or wing is made up of the skin friction (the viscous contribution of drag due to boundary layers) and pressure drag. for 3D (or wings) you get the induced drag as well an if you also take into account the nacelle you have interference drag ... the list goes on.

so in fluid dynamic we just say viscous drag and skin friction is just an aerodynamic concept (probably also to be found in other disciplines)

infikamal5 · January 9, 2015, 10:41

Hi Teschner,

Thanks for your reply,

I calculate the total viscous drag coefficient inside a pipe flow and I wanted to just verify it if is the also the Skin friction coefficient .

so as you said Viscous drag coeff is the skin friction coeff

Thanks a lot

January 9, 2015, 08:47	Viscous Drag	#1
infikamal5 New Member KS5 Join Date: Mar 2012 Location: US Posts: 15 Rep Power: 14	Hi, I would to know if the viscous drag coefficient and the skin friction drag coefficient are the same ?? Thanks

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January 9, 2015, 10:34		#2
t.teschner Senior Member Tom-Robin Teschner Join Date: Dec 2011 Location: Cranfield, UK Posts: 211 Rep Power: 16	Yes (at least I have not heard of a different definition). Viscous drag is caused by boundary layers and hence is the same as skin friction. I think you have the two terms as in aerodynamics you distinguish between a lot of different forms of drag (total drag, induced drag, zero drag, wave drag, interference drag, profile drag, misc drag, pressure drag and skin friction) so here, the profile drag of an airfoil or wing is made up of the skin friction (the viscous contribution of drag due to boundary layers) and pressure drag. for 3D (or wings) you get the induced drag as well an if you also take into account the nacelle you have interference drag ... the list goes on. so in fluid dynamic we just say viscous drag and skin friction is just an aerodynamic concept (probably also to be found in other disciplines)

January 9, 2015, 10:41		#3
infikamal5 New Member KS5 Join Date: Mar 2012 Location: US Posts: 15 Rep Power: 14	Hi Teschner, Thanks for your reply, I calculate the total viscous drag coefficient inside a pipe flow and I wanted to just verify it if is the also the Skin friction coefficient . so as you said Viscous drag coeff is the skin friction coeff Thanks a lot