>    restart;

>    u := (x,y) -> 15* exp( -sqrt(5)*9*Pi*Pi/4*y)*cos(3*Pi/2 *x) + 16 *exp(-sqrt(5)*29241*Pi*Pi/4 *y) *cos(171*Pi/2 *x);
plot3d( u(x,y), x=0..2, y=0..0.09, labels =[`x`, `time`, `u(x,t)`], axes=FRAMED, style=patch);

u := proc (x, y) options operator, arrow; 15*exp(-sqrt(5)*9/4*Pi*Pi*y)*cos(3/2*Pi*x)+16*exp(-sqrt(5)*29241/4*Pi*Pi*y)*cos(171/2*Pi*x) end proc

[Maple Plot]

>