A frictionless, incompressible steady flow field is given by V = 2xyi − y2j (2) in arbitrary units. Let the density be rhoo = constant and neglect gravity. Find expressions for the pressure gradients in both the x and y directions.

Respuesta :

Answer:

pressure gradient in x direction:

[tex] \frac{\partial p}{\partial x} = -\rho 2xy^{2} [/tex]

pressure gradient in y direction:

[tex] \frac{\partial p}{\partial y} = \rho 2y^{3} [/tex]

Explanation:

Here the gravity is neglected and the field velocities is time independent, so we can use a simplify equation to Navier-Stokes.

[tex] \frac{DV}{Dt} = -\frac{1}{\rho} \nabla p [/tex]                                        

V: Field Flow

ρ: Density

p: pressure

Before finding the pressure, let's define the components of the field vector.

[tex] V= 2xyi - y^{2}j [/tex]

[tex] u=2xy [/tex]    [tex] v = y^{2} [/tex]

Now, the x component pressure gradient will be:

[tex] u\frac{\partial u}{\partial x} + v\frac{\partial u}{\partial y} = -\frac{1}{\rho} \frac{\partial p}{\partiala x} [/tex]

[tex] 4xy^{2}-2xy^{2} = -\frac{1}{\rho} \frac{\partial p}{\partial x} [/tex]

[tex] \frac{\partial p}{\partial x} = -\rho 2xy^{2} [/tex]

We can apply the same analyze to find the y component of the pressure gradient. We just need to take the partial derivative from v.

[tex] u\frac{\partial v}{\partial x} + v\frac{\partial v}{\partial y} = -\frac{1}{\rho} \frac{\partial p}{\partial y} [/tex]

[tex] 0-2y^{3} = -\frac{1}{\rho} \frac{\partial p}{\partial x} [/tex]

[tex] \frac{\partial p}{\partial y} = \rho 2y^{3} [/tex]

I hope it helps you! :)

     

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