(*Variable&Parameters*)h=1;ri=0.5;eq=D[u[t,r,θ,z],t]-D[u[t,r,θ,z],r,r]+(1/r)D[u[t,r,θ,z],r]+1/(r^2)D[u[t,r,θ,z],θ,θ]+D[u[t,r,θ,z],z,z];(*InitialandBoundaryconditions*)ic={u[0,r,θ,z]==Exp[-r]};bc={u[t,ri,θ,z]==1,u[t,1,θ,z]==0,PeriodicBoundaryCondition[u[t,r,θ,z],θ==0,TranslationTransform[{0,0,2*Pi,0}]],PeriodicBoundaryCondition[u[t,r,θ,z],z==0,TranslationTransform[{0,0,0,h}]]};(*Solution*)sol=NDSolve[{eq==NeumannValue[0,r==ri]+NeumannValue[1,r==1],ic,bc},u[t,r,θ,z],{t,0,10},{r,ri,1},{θ,0,2*Pi},{z,0,1}];(*Plottingofsolution*)Manipulate[Plot3D[sol,{r,0,1},{θ,0,2Pi}],{t,0,10},{z,0,1}];
