| This thesis presents an experimental study on the flow of magneto-rheological grease (MRG) through microchannels. The flow of MR materials through microchannels can potentially be used as a microvalve in microfluidic and microelectromechanical systems (MEMS) devices. The flow is controlled by injecting the MRG through microchannels with controlled adjustable rates. To study the effect different channel diameter and surface roughness, microchannels made of stainless steel, PEEK, and fused silica materials with nominal internal diameters ranging from 1 mm to 0.075 a (75 mum) are tested. A magnetic field is applied perpendicular to the microchannel flow and is controlled by an input electric current. The pressure drop of the flow is measured across the length of the microchannels. The dynamic pressure drop range and surface roughness effects are also discussed. The results show a significant pressure drop for different magnetic field strengths. The Herschel-Bulkley model for non-Newtonian fluid flow is applied to the experimental results with good agreement. |
