PDE Toolbox solution array along a line, to then find the mean value

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A 2015-1-29

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评论： Bill Greene 2015-1-31

I'm have solved Poisson's equation for simple rectangular geometry using the PDE Toolbox. I exported the solution and mesh and now I want to find u along a line so that I can then find its average.

It is a rectangle with bottom boundary at y = -0.8 and x = -0.5 to 0.4. This is what I was trying to type in the command line:

F = pdeInterpolant(p,t,u);
x = -0.5:0.4;
y = -0.8;
uOut = evaluate(F,x,y)

But this only returns one value. I am looking for an array of values so that I can use mean(uOut) to find the average.

I also want to find the the mean normal component of u into the page at the same position.

Any help greatly appreciated.

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Answer 1

Bill Greene 2015-1-29

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The evaluate function is returning only one value because the length of your x and y vectors is one. Maybe you want something like this:

F = pdeInterpolant(p,t,u);
n = 10;
x = linspace(-.5,.4,n);
y(1:n) = -.8;
uOut = evaluate(F,x,y)

to interpolate along the line between x=-.5 and x=.4

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A 2015-1-30

Thank you very much, this is exactly what I was looking for! Any chance you know how to calculate the normal component into the page (z -direction)? I can only find grad for x and y.

Bill Greene 2015-1-31