[clark.J]

Hello,everyone! Resently,I'm working on verifying the accuracy of my code by mesh refinement.My code is written in Fortran, and is based on FVM.
I choose the benchmark problem--Taylor-Green Vortex. During the computation,the computation domain size is 2π*2π. I impose the initial velocity and pressure field as following:
u(x,y,t)=-sin(x)cos(y)exp(-2νt)
v(x,y,t)=cos(x)sin(y)exp(-2νt)
p(x,y,t)=0.25(cos(2x)+cos(2y))exp(-4νt)
The folw is two-dimensional,laminar and unsteady.The density ρ is 1,and the kinetic viscosity is 0.01;with periodic conditions at the boundaries x=0,x=2π,
y=0 and y=2π.
Is that right?During the computation,I just give the velocity and pressure field at t=0.
In my thought,my code is second order,but the result shows that it is less than first order!
Please point out my mistakes, and I will be very grateful!