Help me solving this differential equation please

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  • #1
ahm_11
6
0
μ[uyy + uzz] - ∂p/∂x = 0 ... (1)

∂u/∂x = 0 ;

i tried assuming u(y,z) = Y(y)Z(z)

so (1) becomes ... μ[ZYyy + YZzz] - ∂p/∂x = 0

hence (1/Y)*Yyy + (1/Z)*Zzz = (R/YZ) = -λ2
where, R = (1/μ)*∂p/∂x

now Yyy + λ2Y = 0 ... can be solved easily but what about the remaining part ... i couldn't solve it due to the constant ...
 
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  • #2
ahm_11 said:
μ[uyy + uzz] - ∂p/∂x = 0 ... (1)

∂u/∂x = 0 ;

i tried assuming u(y,z) = Y(y)Z(z)

so (1) becomes ... μ[ZYyy + YZzz] - ∂p/∂x = 0

hence (1/Y)*Yyy + (1/Z)*Zzz = (R/YZ) = -λ2
where, R = (1/μ)*∂p/∂x

now Yyy + λ2Y = 0 ... can be solved easily but what about the remaining part ... i couldn't solve it due to the constant ...
Is there any other information? In particular, is there anything known about p?
 
  • #3
∂p/∂x = constant

Some boundary conditions:
x=0 , x=L ... ∂u/∂x = 0 , v=0 , w=0 , ∂p/∂x = constant
y=-a,y=a ... u=0,v=0,w=0, ∂p/∂y=0
z=-b,z=b ... u=0,v=0,w=0, ∂p/∂z = 0
 
  • #4
ahm_11 said:
μ[uyy + uzz] - ∂p/∂x = 0 ... (1)

∂u/∂x = 0 ;

i tried assuming u(y,z) = Y(y)Z(z)

so (1) becomes ... μ[ZYyy + YZzz] - ∂p/∂x = 0

hence (1/Y)*Yyy + (1/Z)*Zzz = (R/YZ) = -λ2
where, R = (1/μ)*∂p/∂x

now Yyy + λ2Y = 0 ... can be solved easily but what about the remaining part ... i couldn't solve it due to the constant ...

Since [itex] \partial{p}/\partial{x} = c[/itex] (a constant) your DE is just
[tex] u_{yy} + u_{zz} = k, [/tex]
where [itex] k = c/ \mu [/itex] is a constant. Your condition [itex] u_x = 0[/itex] means that 'x' does not appear anywhere in the problem.

RGV
 

1. What is a differential equation?

A differential equation is a mathematical equation that describes the relationship between a function and its derivatives. It involves the derivative of one or more dependent variables with respect to one or more independent variables.

2. How do I solve a differential equation?

There are various methods for solving differential equations, including separation of variables, substitution, and using integrating factors. The method used depends on the type and complexity of the differential equation.

3. What is the purpose of solving differential equations?

Differential equations are used to model and describe real-world phenomena in fields such as physics, engineering, economics, and biology. By solving these equations, we can understand and predict the behavior of systems and make informed decisions.

4. What are the challenges in solving differential equations?

The challenges in solving differential equations include identifying the type of equation, choosing the appropriate method, and finding the general solution. Some equations may also be difficult or impossible to solve analytically, requiring numerical methods for approximation.

5. Can I use software to solve differential equations?

Yes, there are many software programs and online tools available for solving differential equations. These programs use numerical methods to approximate the solutions, making it easier and quicker to obtain results. However, it is important to understand the underlying principles and methods in order to properly interpret the results.

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