What is the Difference between Re=0 and Re=0.01 in Simulation of Viscoelastic Flow
 

Hello,

I have a question for quite a long time. When people simulate viscoelastic flow, they usually do the simulation at Reynolds Number Re=0, in order to simulate the creeping flow. However there is no physical meaning for Re=0, except that the velocity is 0. But when the velocity is 0 then actually there is no 'Flow'.

So why people simulate Re=0?

Why not do the simulation for Re=0.01 or smaller instead of Re=0? Is there great difference between the results of Re=0 and Re=0.01?

Thanks for your reply in advance!

BTW, when people simulate the case for Re=0, they just neglect the convective term in the momentum eqn.

one difference is, when we consider the elastic number E=Wi/Re, where Wi is the Weissenberg number, then Re=0 and Re=0.01 are great different. But the problem is the elastic number can be also calculated by E= viscosity*relaxation time/(density*length*length).

still need help

thanks

some models can't be used for Re=0 or Wi=0 because of being this numbers in denominator.
after this, Re=.000001 is creeping flow and in viscoelastic viscous forces ( they are dominant in creep flow even for newtonian) are very important.

Could you please give me some examples that can not be used for Re=0?

Re=0 means simply that you are assuming:

Re * (du/dt + div (u u) + grad p') = Lap u = 0

this is more a mathematical assumption than a physical condition