Simplifying a Boundary Layer Theory Equation

In summary, the problem is to write the equation d\Psi/dy(d^2\Psi/dxdy)-d\Psi/dx(d^2\Psi/dy^2=-\nu(d^3\Psi/dy^3) in the form of -ff''=f''', where \Psi(x,y)=-sqrt(V*\nu*x)f(\eta) and f(\eta)=integral(from 0 to \eta)(\Pi')*(\overline{\eta})*d(\overline{\eta}) with \overline{\eta} as a dummy variable. The attempt at a solution involved taking derivatives using Maple, but the solution was not found. The original equation was the Navier
  • #1
juice34

Homework Statement


The problem is write this

d[tex]\Psi[/tex]/dy(d^2[tex]\Psi[/tex]/dxdy)-d[tex]\Psi[/tex]/dx(d^2[tex]\Psi[/tex]/dy^2=-[tex]\nu[/tex](d^3[tex]\Psi[/tex]/dy^3)

in the form of -ff''=f'''
where

[tex]\Psi[/tex](x,y)=-sqrt(V*[tex]\nu[/tex]*x)f([tex]\eta[/tex])

f([tex]\eta[/tex])=integral(from 0 to [tex]\eta[/tex])([tex]\Pi[/tex]')*([tex]\overline{\eta}[/tex])*d([tex]\overline{\eta}[/tex]) where [tex]\overline{\eta}[/tex] is a dummy variable

Homework Equations

[tex]\prod[/tex]

The Attempt at a Solution


I have just tried taking the derivatives using maple but to no avail. Please help! Also note that the small v is a multiplier and nothing is raised to the power. Please excuse my formatting.
 
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  • #2
also note initally the first equation was the navier stokes equation, then i substituted in the stream function.
 
  • #3
Finally got the solution
 

1. What is the boundary layer?

The boundary layer is a thin layer of fluid that forms on the surface of an object when it is exposed to a moving fluid such as air or water. It is characterized by a gradual change in velocity and other fluid properties from the surface of the object to the free stream flow.

2. Why is boundary layer theory important in fluid dynamics?

Boundary layer theory is important because it helps us understand the behavior of fluids near solid surfaces. This is crucial in many engineering applications, such as aerodynamics, where the interaction between the fluid and the surface can greatly affect the performance of the object.

3. What factors affect the development of the boundary layer?

The development of the boundary layer is affected by several factors, including the fluid properties (such as viscosity and density), the velocity of the fluid, the shape and roughness of the surface, and the angle of attack of the object.

4. How is the thickness of the boundary layer determined?

The thickness of the boundary layer is determined by the balance between the viscous forces acting on the fluid and the inertial forces of the free stream flow. This is known as the boundary layer equation and can be solved using various mathematical models.

5. What are some practical applications of boundary layer theory?

Boundary layer theory has numerous practical applications, including the design of aircraft wings, wind turbines, and sports equipment such as golf balls. It is also used in the analysis of fluid flow in pipes, heat exchangers, and other industrial processes.

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