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## Main Question or Discussion Point

I am solving the heat equation in a non comercial C++ finite elements code with explicit euler stepping, and adaptive meshes (coarse in the boundaries and finer in the center). I am aware the CFL condition for the heat equation depends on dt/h**2 for the 1D, 2D, 3D case. When I solve the equation in 2D this principle is followed and I require smaller grids following dt<h**2.

But in 3D the problem seems to be requiring finner and finer grids as I decrease the timestep in what appears to be a dt/h**3 behaviour. Does anyone have an idea what could be happening? is the CFL no longer valid in FEM and 3D? What other factors could be influencing?

But in 3D the problem seems to be requiring finner and finer grids as I decrease the timestep in what appears to be a dt/h**3 behaviour. Does anyone have an idea what could be happening? is the CFL no longer valid in FEM and 3D? What other factors could be influencing?