Consider the following steady, two-dimensional, incompressible velocity field:, where a is a constant. Calculate the pressure as a function of x and y.
Step: 1
Write the expression for steady, two dimensional, incompressible velocity field.
Write the velocity components u and v.
Find the differentiation of velocity components.
Find the differentiation of velocity components with respect to time.
Step: 2
Check the velocity field satisfies the two dimensional, incompressible continuity equation or not.
Write the two dimensional continuity equation.
Substitute for
and
for
Hence continuity equation satisfied.
Step: 3
Write the x-component of the two dimensional incompressible Navier-Stokes equation.
Here, is density,
is gravity along x direction, and
is dynamic viscosity.
Substitute 0 for , 0 for
, 0 for
,
for
,
for
,
for u,
for v,
for
, 0 for
, and 0 for
Now, differentiate the above equation with respect to y.
Now, take the y-component of the two dimensional incompressible Navier-Stokes equation.
Substitute 0 for , 0 for
, 0 for
,
for
,
for
, 2ax for
,
for u,
for v, 0 for
, 0 for
, and 0 for
Now, differentiate the above equation with respect to x.
Since Hence P is not a smooth function of x and y.
Therefore, the pressure as a function of x and y cannot be calculated.