Changing the axes of a contour plot

Question

I have a contour plot that is currently being plotted in the default x-y plane at some z location. I need to plot this in the y-z at some x-location. Does anyone know how to change the code below to allow this?

Contour Plot

[~, one] = contourf(y_grid, z_grid, U_mean, 80,'edgecolor','none'); 
one.ContourZLevel = 8.125;

I tried a normal contour plot, and I was expecting the plot to appear in the y-z plane.