This message says, that the solution of the linear system of equations for the kinetic energy of turbulence at the current iteration has negative values at the reported number of mesh cells. Normally the reason for that is purely numerical, i.e. either bad convergence, or bad mesh, or both. Of course, it can also happen, when a user adds a negative source term to the “k” equation. Physically “k” cannot be negative. When such negative values occur locally, the solver replaces them through a mean positive value computed from the surrounding cells. Keywords: Kinetic Energy, Negative K, Turbulence, TKE,