Question

Which of the variables in the equation \(\rho\frac{Du}{Dt}=-\frac{\partial p}{\partial x}+\frac{\partial \tau_{xx}}{\partial x}+\frac{\partial \tau_{yx}}{\partial y}+\frac{\partial \tau_{zx}}{\partial z}+\rho f_x\) will become zero for formulating Euler equation?

(a) fx, τyx, τzx

(b) τxx, τyx, u

(c) τxx, τyx, τzx

(d) τxx, p, τzx

I have been asked this question in semester exam.

I'd like to ask this question from Euler Equation in portion Governing Equations of Fluid Dynamics of Computational Fluid Dynamics

Answer 1

Correct option is (c) τxx, τyx, τzx

To explain I would say: τxx, τyx, τzx represent shear stresses due to viscous effects; u is the x-velocity; fx is the body force and p is the pressure. τxx,τyx,τzx should become zero for the flow to be in-viscid and the equations to be Eulerian.