Easy Fluid Problem: Find Stream Function & Pressure

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In summary, a stream function is a mathematical concept used in fluid mechanics to describe the flow of a fluid. It is found by solving a partial differential equation and has physical significance in visualizing and analyzing fluid flow. It is related to pressure through the Bernoulli's equation, but is only suitable for ideal fluid flow problems and not for more complex problems.
  • #1
600burger
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Homework Statement



a. Given potential flow, find stream function and velocity components.
b. Compute pressure along the x-axis and plot it.

Homework Equations



Psi = 2axy

The Attempt at a Solution



So, I got the psi from phi (above) but i don't understand how I am to go from stream function Psi to the pressure distrobution...
 
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  • #2
From the stream function you can calcualte the velocity field.
You can guess that it is possible to get the pressure, just think to Bernouilli.
Anyway, plug the velocity field into the Navier-Stokes equations and you will get the pressure (gradient).
 
  • #3


I would approach this problem by first understanding the concept of stream function and its relationship to potential flow. The stream function is a mathematical function used to describe the flow of a fluid in two-dimensional space. It is defined as the flow rate per unit width perpendicular to the flow direction. In potential flow, the stream function is related to the velocity components through the continuity equation.

To find the stream function in this problem, I would use the given equation for potential flow and apply it to the definition of stream function. This would give me the stream function as a function of x and y.

Once I have the stream function, I can use it to find the velocity components along the x-axis by taking the partial derivative of the stream function with respect to x. This would give me the u component of velocity, while the v component would be zero since there is no flow in the y-direction.

To compute the pressure along the x-axis, I would use the Bernoulli's equation, which relates the pressure to the velocity and stream function. By substituting the velocity components and the stream function into the equation, I can solve for the pressure at any given point along the x-axis.

After computing the pressure at different points along the x-axis, I can plot it to visualize the pressure distribution. This can help me understand the behavior of the fluid in the given potential flow and identify any areas of high or low pressure.

In summary, to solve this easy fluid problem, I would use the given equation for potential flow to find the stream function, and then use it to calculate the velocity components and pressure along the x-axis. Finally, I would plot the pressure distribution to gain a better understanding of the fluid flow.
 

1. What is a stream function in fluid mechanics?

A stream function is a mathematical concept used to describe the flow of a fluid. It is a function that represents the streamlines of a fluid flow, with each streamline representing the path of a fluid particle. The value of the stream function at any point in the fluid gives the distance from a reference line along the streamline passing through that point.

2. How do you find the stream function in an easy fluid problem?

The stream function can be found by solving the stream function equation, which is a partial differential equation that describes the fluid flow. This equation is solved using mathematical techniques such as separation of variables or the method of characteristics. Once the stream function is found, it can be used to determine the velocity and other properties of the fluid flow.

3. What is the physical significance of the stream function?

The stream function is a useful tool in fluid mechanics as it helps visualize and analyze the flow of a fluid. It allows us to determine the direction of flow, identify areas of stagnation or recirculation, and calculate the volume flow rate through a given cross-section of the fluid. It also helps simplify the mathematical analysis of fluid flow problems.

4. How does the stream function relate to the pressure in a fluid?

The stream function and pressure in a fluid are related through the Bernoulli's equation, which states that in a steady, inviscid, and incompressible flow, the sum of the fluid's kinetic, potential, and pressure energies remains constant along a streamline. This relationship allows us to find the pressure at any point in the fluid by knowing the stream function and vice versa.

5. Can the stream function be used for all types of fluid flow problems?

The stream function is a concept often used in ideal fluid flow problems, where the fluid is assumed to be inviscid and incompressible. It is not suitable for more complex fluid flow problems, such as turbulent flow or flow with viscosity and compressibility effects. In these cases, other mathematical techniques and equations must be used to analyze the fluid flow.

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