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January 31, 2011, 17:29 |
Purpose of streamlines in unsteady flow
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#1 |
Senior Member
TWB
Join Date: Mar 2009
Posts: 400
Rep Power: 19 |
Hi,
I have seen diagrams of airfoil with streamlines drawn. It helps to show the velocity vectors of the flow around the airfoil. However, does streamlines help in the analysis of unsteady flows, such as an airfoil moving up and down? Is there any useful information which can be extracted? Thanks! |
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February 1, 2011, 10:30 |
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#2 |
Member
private
Join Date: Mar 2009
Posts: 74
Rep Power: 17 |
Streak lines can be useful for visualization.
One way: Create an imaginary particle at points of interest (x, y). Follow the particle in a Lagrangian frame. Example: Dx/Dt = u, Dy/Dt = v, Dz/Dt = w so x(t+dt) = x(t) + u*Dt, etc. following the particle through the flow. The three equations can be integrated explicitly [use u(x, t)], implicitly [use some combination of u(x,t) and u(x+dx, t+dt) estimates]. The u's, v's and w's are interpolated from your CFD solutions at the various (x,y,z,t). Implicit schemes and various Runge-Kutta schemes are available. I'm sure other folks will correct, extend, and clarify this outline! otd |
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