2D parabolic equations CNL-GZE COVID-19 C∞-semigroups Eyring–Powell Faedo–Galerkin method Fourier multipliers Jacobi elliptic function method PDE’s stabilization Pascal bases automatically satisfying specified conditions Riccati–Bernoulli sub-ODE method Shishkin mesh acoustic boundary conditions analytic semigroups appropriate transformation technique backward nonlocal wave equation bacterial motion bic Book Industry Communication::G Reference, information & interdisciplinary subjects::GP Research & information: general bic Book Industry Communication::P Mathematics & science biological aggregation chemotaxis model coinfection convection diffusion problems convection–diffusion problem delay differential equations diffusion diffusion equations energy functional feedback control fractional Zakharov system