def METHOD_NAME(self, dx, D, umax):
    """
    https://en.wikipedia.org/wiki/Numerical_solution_of_the_convection%E2%80%93diffusion_equation#Solving_the_convection%E2%80%93diffusion_equation_using_the_finite_difference_method
    """
    h = 2 * D / (self.rho * umax)
    dt = dx**2 / (2 * D)
    return h, dt