Study of complex turbulent flows over rough walls and flow of non-newtonian fluid through model porous media

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The objectives of this proposal are to study complex near-wall turbulent flows and flow of non-Newtonian fluid through porous media. The turbulence research will focus on the investigation of roughness effects on turbulent wall jets, pressure gradient boundary layers, and shallow wakes in an open channel. The values of the pressure gradient parameter will be varied from mild to strong. A planar and stereo particle image velocimetry (PIV) will be used to conduct the velocity measurements. The instantaneous velocity field will be used to identify coherent structures, and the dynamic role of these structures on turbulence production in the various turbulent flows and surface conditions will be elucidated. From the PIV data, iso-contours and profiles of the time averaged mean velocity and the various terms in the transport equations for turbulent kinetic energy and Reynolds stresses will be evaluated. A planar laser induced fluorescence will be used to study roughness effects on scalar transport and mixing process in the wall jets and wakes. The wall jet results will provide insight into the interaction between the inner and outer layers, and how this interaction is modified by specific roughness. The pressure gradient experiments will provide information on the combined effects of roughness and pressure gradients on the turbulent structure. The physical understanding obtained from the turbulence research and the high quality data sets will be used in the future to guide the development of accurate models for predicting turbulent flows of engineering importance. The porous media will comprise arrays of acrylic rods placed perpendicular and parallel to flow in a rectangular channel. The rods will fill only a fraction of the space between the top and bottom walls of the channel. A variety of non-Newtonian fluids will be studied. The rheological properties of the fluids will be measured. A PIV will be used to study the velocity field. The effects of variables such as porosity, filling fraction of channel height and specific fluid on onset of recirculation within the rods, and penetration of the plain flow into the porous media will be studied. The research will provide opportunity to train highly qualified personnel and provide substantial economic benefits to Canada.