COBEM99

SR26 Reologia

Title:

A GENERALIZED BOUNDARY LAYER FORMULATION TO FORCED CONVECTION HEAT TRANSFER OF POWER-LAW FLUIDS

Summary :

THE NON-NEWTONIAN BEHAVIOR OF CERTAIN MATERIALS OCCURS IN SEVERAL INDUSTRIAL APPLICATIONS, NAMELY POLYMER EXTRUSION, GREASES, COSMETICS AND DRILLING MUDS. THE BOUNDARY LAYER FORMULATION IS A VERY POPULAR TOOL. TO STUDY SUCH TYPE OF FLOWS, ALTHOUGH IN SOME SITUATIONS, AS AT THE BOUNDARY LAYER SEPARATION POINT, THIS FORMULATION PRESENTS SOME LIMITATIONS. IN THIS WORK A GENERALIZED BOUNDARY LAYER FORMULATION IS UTILIZED IN THE ANALYSIS OF THE FORCED CONVECTION OF NON-NEWTONIAN POWER-LAW FLUIDS. IN THIS FORMULATION THE CLASSIC DIVISION OF THE FLOW FIELD IN VISCOUS AND INVISCID REGIONS DISAPPEARS, MAKING UNNECESSARY ANY TYPE OF VISCID-INVISCID INTERACTION. THE RESULTING PARTIAL DIFFERENTIAL EQUATIONS ARE REDUCED INTO A SET OF ORDINARY EQUATIONS, TROUGH A SIMILAR VARIABLE TRANSFORMATION, ANALOGOUSLY THE TRANSFORMATION USED IN THE DEDUCTION OF THE FALKNER-SKAN EQUATION, WHICH IS A PARTICULAR CASE OF THE PRESENT FORMULATION. THE RESULTING EXPRESSIONS ARE SOLVED NUMERICALLY AND THE RESULTS ARE PRESENTED FOR MANY VALUES OF THE POWER-LAW INDEX (N), SHOWING ITS INFLUENCE IN THE HEAT TRANSFER COEFFICIENT AT THE WALL. ALSO A STUDY OF THE TEMPERATURE FIELD AT THE SEPARATION REGION WILL BE MADE. KEY WORDS: BOUNDARY LAYER, POWER-LAW FLUIDS, FORCED CONVECTION

Author :

Cruz, Daniel Onofre de Almeida
Macêdo, Emanuel Negrão
Manescky, Carlos Edilson
Miranda, José Maria Oliveira

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