| The transfer (cascade) of energy from large to small scales in turbulent flows is the result of nonlinear processes, such as vortex stretching, determined by the velocity gradient tensor. The dynamics of the velocity gradients depends crucially on the hessian, the second derivative matrix, of pressure. We demonstrate here, based on numerical and experimental results, that on average, the pressure term tends to reduce the nonlinearity, the more so as the scale gets closer to the dissipation range. The fluctuations of the pressure hessian can be simply parametrized in the case of homogeneous turbulence. |
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