An Inverse Optimization Of The Heat Transfer In A 2D Channel Flow Based On The Extremum Principle Of Entransy Dissipation

An inverse convection heat transfer in a two-dimensional channel mounted with square ribs was concerned in the present work.A simplified conjugate gradient method(SCGM)was adopted for optimizing the convection heat transfer.The optimal pitch ratio of the ribs was found to get the most efficient heat transfer in different ribs numbers.The physical model of this paper was built at first.The entransy dissipation was used to the objective function for inversion,then introduces the optimization method,the conjugate gradient method.A two-dimensional channel with periodic transverse square ribs is considered.The heat exchange situation is analyzed by numerical simulation.There was given two boundary conditions,the isothermal boundary condition and the fixed heat flux boundary condition.the numerical simulation result shows the relations between Nusselt number and the entransy dissipation with the pitch ratio for various rib numbers.The results indicate that for a fixed heat flux boundary condition,the heat transfer process is optimized when the entransy dissipation is minimized,while for a fixed temperature boundary condition the heat transfer is optimized when the entransy dissipation is maximized.The effect of the ribs on the heat transfer was analyzed by solving the direct problem.Now the attention is turned to the process for optimizing the pitch ratio.the conjugate gradient method(CGM)combined with the sensitivity method and the adjoint gradient method,then through FLUENT and the dynamic mesh model to optimize the turbulator structure,and starting from different initial positions.the comparing the results with the direct problem was an implementation.In the calculation process,the algorithm has been modified many times,and the calculation results of higher precision are obtained.In the same way as the direct problem,the inverse optimization of different ribs numbers(from less to more)is carried out to find the optimal value.In addition,in the case of fixed heat flux boundary condition,the distribution of the entransy dissipation value of the fire product has a local extreme point.When using the simplified conjugate gradient method,the results of the search stay near the local extreme point.Again with this new method to the inversion,the final results show that we can search to reach the best near the extreme value point both of two kinds of boundary conditions,The method is proved to be effective and it is proved that the correctness of the entransy dissipation extremum principle.The inversion method is used to optimize the heat transfer situation,which can get the optimal result faster and improve the efficiency.The calculation method for convective heat transfer optimization is worth promoting.