Hi everyone, I am new of Mathematica.. I am trying to solve a set of partial differential equations in 4 four variables (x,y,z,t).

When I set up the resolution as follows:

[...]

PD equations

[...]

bcs = {DirichletCondition[{Ux[x, y, z, t] == 0., Uy[x, y, z, t] == 0.,
      Uz[x, y, z, t] == 0.}, True]};
ics = {Ux[x, y, z, 0] == 0, Uy[x, y, z, 0] == 0, Uz[x, y, z, 0] == 0, 
   T[x, y, z, 0] == 
    Piecewise[{{Subscript[T, 
       hot], (x - (l/2.0))^2 + (y - (d/2.0))^2 + (z - (h/2.0))^2 <= 
        hotSphereRadius^2}}, Subscript[T, eq]]};

pde = Operator == {0, 0, 0, 0};

{Ux0, Uy0, Uz0, T0} = 
  NDSolveValue[{pde, ics, bcs}, {Ux, Uy, Uz, T}, {t, 0, Subscript[tt, 
    last]}, {x, y, z} \[Element] mesh, 
   DependentVariables -> {Ux, Uy, Uz, T}, Method -> Automatic];

I get the following error:

LinearSolve::mcovl: The computation encountered machine-number overflow. Only machine-number code is available for sparse matrices. If your matrix is not too large, consider trying again after using Normal on the matrix.

Have you ever encountered this error? What would you try to do to solve this issue? I can provide more infos if needed. Thanks in advance!

Enrico