References to the algorithm: 1. Guan, Yifei, and Igor Novosselov. "Two relaxation time lattice Boltzmann method coupled to fast Fourier transform Poisson solver: Application to electroconvective flow." Journal of computational physics 397 (2019): 108830. 2. Guan, Yifei, and Igor Novosselov. "Numerical analysis of electroconvection in cross-flow with unipolar charge injection." Physical Review Fluids 4, no. 10 (2019): 103701. Flag = 1, intialize the problem. Otherwise, continue from previous state. Perturb = 1 to perturb the flow There are two places for CFL. They need to be the same. Fast Poisson v2 should be faster than Fast Poisson