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This blog is a good start: Using Mathematica to Simulate and Visualize Fluid Flow in a Box It fully solves 2D problem of one moving boundary and gets nice vertex flows: There are detailed descriptions of proper equations and numerical discretization. You can generalize to 3D. I would look also in latest V10 functionality to see if anything can be ...


3

The same problem also appears in the related function ClebschGordan. This is indeed a bug which appears when Mathematica is given symbolic parameters instead of specific integers or half-integers. We can check that the first result in the question is incorrect by using the explicit sum definition of ThreeJSymbol given in the documentation under Properties: ...


3

Just to expand on what @eldo has written. I found that this odd behavior happens for all odd $n$ values where $n$ is the argument of this function:- f[n_] := Module[{r1, r2, r3}, r1 = ThreeJSymbol[{a, 0}, {b, 0}, {c, 0}] /. {a -> n, b -> n, c -> 0}; r2 = ThreeJSymbol[{a, 0} /. a -> n, {b, 0} /. b -> n, {c, 0} /. c -> 0]; r3 = ...


2

Line1: ThreeJSymbol is evaluated before replacement. Line2: ThreeJSymbol is evaluated after replacement. To give another example: D[x^2, x] /. x -> 2 4 D[x^2 /. x -> 2, x] 0


3

ParametricPlot3D and ParametricPlot accept a wide range of nested lists of expressions to specify a function or functions to be graphed. Let's discuss ParametricPlot3D. ParametricPlot is similar, with lists of length 2 replacing lists of length 3 where appropriate. There are two types of specifications List[expr,...] List[List[...],...] where expr ...



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