Concluding Remarks and Future Work

Abstract

This book investigated the influence of the presence of a porous layer covering a surface where a jet collides. This work reviewed and compiled a systematic study on impinging jets on bare and covered walls, which was carried out in the last few years at ITA, Brazil, and considered both laminar [Graminho and de Lemos (Numer Heat Transf Part A Appl 54(2):151–177, 2008), de Lemos and Fischer (Numer Heat Transf Part A Appl 54:1022–1041, 2008), Dórea and de Lemos (Inter J Heat Mass Transf 53:5089–5101, 2010)] and turbulent flow regimes [Graminho and de Lemos (Inter J Heat Mass Transf 52:680–693, 2009), Fischer and de Lemos (Numer Heat Transf Part A Appl 58:429–456, 2010), de Lemos and Dórea (Numer Heat Transf Part A Appl 59(10):769–798, 2011)]. By that, a self-contained text was put together in order to convey to the interested reader the major steps and results achieved on such research topic. Two energy modes were applied, namely 1EEM and 2EEM, based respectively on the Local Thermal Equilibrium (LTE) and Local Thermal Non-Equilibrium hypotheses (LNTE). It was observed that the Reynolds number and porosity strongly influences the stagnation Nusselt value while the porous layer thickness affects more intensely the distribution of Nu along the plate. Cases with low porosity and highly permeable layers of porous material tend to yield better heat absorption/release rates when compared with a bare wall case. Regardless of the model used, increasing the thermal conductivity ratio is always beneficial to heat transfer enhancement form the hot wall. Ultimately, results in this work might be useful to engineers designing systems that make use of impinging jets over thermally conducting porous materials.