An Integral Variational Equation for Transport Processes in a Moving Fluid

An integral variational equation can adequately describe heat, mass, and momentum transfer in a moving chemically reactive fluid. The Euler-Lagrange equations corresponding to the suggested variational equation are identical to the equations of entropy, momentum, angular momentum, and mass balance. The constructed Lagrangian density relates energy change in the system to the work and energy dissipation of the system. For steady-state processes, the Lagrangian density includes convective energy flow through the system boundary, energy dissipation in the system, and work of the system. The proposed variational equation is equivalent to the expansion of the principle of minimum energy dissipation.