Simultaneous Drag Reduction and Heat Transfer Enhancement for Slit Flow by Means of Coating One Wall with a Magnetic Fluid

In this study the laminar flow and heat transfer in slit flow are examined, when the lower wall is coated by a magnetic fluid. Being held in place by means of magnets, drag reduction and simultaneous heat transfer enhancement (relative to the case of no coating) are possible. While 400 percent is an upper limit for drag reduction the heat transfer enhancement has (theoretically) no upper bound. Heat transfer enhancement above 400 percent is possible only with a decrease in the flow rate (negative drag reduction). These idealized theoretical results are severely limited by reality. The stability of the magnetic coating (for whatever reason) may not be sufficient to be used in practice.