Can someone explain this plot of the Orr Sommerfeld equation?

In summary, the Orr Sommerfeld equation is a partial differential equation used to describe disturbances in fluid flows, taking into account both viscosity and inertia. It is derived from the Navier-Stokes equations and is commonly used in the study of turbulence and flow stability. The plot of the equation shows the growth rate and frequency of disturbances, which can indicate the stability of the flow. The equation is frequently used in research to study the transition to turbulence and can provide insight into the effects of different parameters on flow stability. While it usually requires numerical methods to solve, there may be cases where analytical solutions are possible.
  • #1
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This is a plot for understanding the stability of flows through the orr sommerfeld equation.
However, I find it really hard to understand. The plot by itself is a little weird, what is it trying to convey?
Spectrum_OS.jpg
 
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  • #2
I feel like I typically see these two axes flipped, but the image is a representation of the eigenvalue spectrum where ##Im(\lambda)## is a frequency and ##Re(\lambda)## is a growth rate (as generally ##c## is assumed to be complex, ##c = c_r + ic_i##). If ##Re(\lambda) > 0## then that eigenvalue is unstable.
 

FAQ: Can someone explain this plot of the Orr Sommerfeld equation?

What is the Orr Sommerfeld equation?

The Orr Sommerfeld equation is a partial differential equation that describes the evolution of disturbances in a fluid flow. It takes into account the effects of both viscosity and inertia and is commonly used in the study of turbulence and stability of fluid flows.

How is the Orr Sommerfeld equation derived?

The Orr Sommerfeld equation is derived from the Navier-Stokes equations, which govern the motion of viscous fluids. It is a linearized version of these equations, meaning that it only considers small disturbances from a steady-state flow.

What does the plot of the Orr Sommerfeld equation show?

The plot of the Orr Sommerfeld equation typically shows the growth rate and frequency of disturbances in a fluid flow. These values can give insight into the stability of the flow, with larger growth rates indicating a more unstable flow.

How is the Orr Sommerfeld equation used in research?

The Orr Sommerfeld equation is frequently used in research to study the stability and transition to turbulence in fluid flows. It can also be used to analyze the effects of different parameters, such as Reynolds number and flow geometry, on the stability of a flow.

Can the Orr Sommerfeld equation be solved analytically?

In most cases, the Orr Sommerfeld equation cannot be solved analytically and requires numerical methods to obtain solutions. However, for simple flow geometries and boundary conditions, analytical solutions may be possible.

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