Simplifying a Boundary Layer Theory Equation

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SUMMARY

The discussion focuses on simplifying a boundary layer theory equation represented as dΨ/dy(d²Ψ/dxdy) - dΨ/dx(d²Ψ/dy²) = -ν(d³Ψ/dy³). The equation is reformulated into the form -ff'' = f''', where Ψ(x,y) = -√(Vνx)f(η). The function f(η) is defined as the integral from 0 to η of (Π')*(η̄)d(η̄), with η̄ as a dummy variable. The user attempted to derive the equation using Maple but encountered difficulties.

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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.
 
Last edited by a moderator:
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also note initally the first equation was the navier stokes equation, then i substituted in the stream function.
 
Finally got the solution
 

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