The pressure velocity correlation in reactive turbulent flows

Analysis is made of the often-neglected correlation between velocity and pressure gradient fluctuations which occurs in the turbulent kinetic energy equation (TKEE). Restricting attention to this correlation for normal turbulent flames in premixed gases using high activation energy asymptotics, a model is generated for the correlation. Splitting the velocity field into solenoidal and irrotational components, it is shown that the acoustic field can dominate the vortical field under several circumstances, in which case the TKEE is not a turbulence equation but an acoustic equation. Under conditions where the vortical field is dominant the pressure-velocity correlation is shown to be essential to the TKE balance.