Change solver method back to multigrid solver

This is currently the faster solver

problems/film-on-substrate.parset

@@ -51,7 +51,7 @@ initialDeformation = "x"
 #############################################
 
 # Inner solver, cholmod or multigrid
-solvertype = cholmod
+solvertype = multigrid
 
 # Number of homotopy steps for the Dirichlet boundary conditions
 numHomotopySteps = 1
@@ -148,4 +148,4 @@ mooneyrivlin_energy = log # log, square or ciarlet; different ways to compute th
 # log: Generalized Rivlin model or polynomial hyperelastic model, using  0.5*mooneyrivlin_k*log(det(∇φ)) as the volume-preserving penalty term
 # square: Generalized Rivlin model or polynomial hyperelastic model, using mooneyrivlin_k*(det(∇φ)-1)² as the volume-preserving penalty term
 
-[]
\ No newline at end of file
+[]