There is nothing to do.
If you force your system strongly, energy will build up and your hydrodynamic flow will become more and more intricate. At the same time, the dissipation becomes more and more efficient since it is proportional to the spatial derivative of the velocity field. You reach a steady state when both effects compensate each other.
The point about turbulence is that for a given forcing and viscosity, the system finds a steady state on its own. If you force weakly (or if the viscosity is large) this steady state is smooth and there is no turbulence. On the other hand for a strong forcing (or a vanishing viscosity) the steady state is turbulent.
Note that you will have to be careful in your DNS. Indeed, if your steady state is turbulent, you will need a very fine space-time grid. In practice, this is a strong limitation. If your numerical codes fails, reduce the forcing (or increase the viscosity) until it works. Hopefully, your computer will be powerful enough for you to observe a turbulent state. To get an idea of how fine your grid should be, you can use Kolmogorov micro-scales. These give an estimate of the scales at which dissipation takes place.