# Final-2013.pdf - SECTION: NAME: CBE 320 Transport Phenomena...

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SECTION:NAME:CBE 320December 16, 2013Transport PhenomenaFinal ExamPart A: Short Answer1.(5 pts.) What are theSI unitsof the following:a.NAb.jAc.DABd.kxe.cA
2.(5 pts.) Write down the Stefan-Boltzmann law for gray (nonblack) bodies. Define each quantity andgive their SI (i.e., MKSA) units.1
3.(10 pts.) Consider a non-isothermal flow problem for mixtures with length, velocity and temperaturescaleslscript0,v0andT1-T0, respectively. Recall the following definitions of some basic dimensionlessgroups:Re=lscript0v0ρμPr=ˆCpμkSc=μρDABBr=μv20k(T1-T0)Gr=(T1-T0)lscript30ν2Grω=(ωA1-ωA0)lscript30ν2Express each of the following dimensionless groups as a ratio of forces or phenomena (e.g., Re=inertial forces/viscous forces).a.ReScb.RePrc.Grω/Re2d.Bre.GrPr2
4.(5 pts.) Forced-convection energy transport from a sphere is described the following correlation forthe mean Nusselt number:Num= 2 + 0.6Re1/2Pr1/3.What is the appropriate correlation for the dimensionless mean mass transfer coefficient for forced-convection mass transfer from a sphere?5.(5 pts.) A mass balance for speciesAin a mixture is written below.ρADt=ρDAB2ωA+rA.Simplify this expression for a stagnant liquid mixture.3
6.(5 pts.) Fluid between two parallel disks (radiusR) is set in motion because the top disk is rotated atangular velocityΩ. Write an integral expression for the torque exerted by the fluid on bottom disk interms of the appropriate stress tensor components.7.(5 pts.) Explain in words (use expressions too if you wish) whykx,locfor mass transfer from a solidsphere increases as the flow becomes more turbulent.8.(5 pts.) Consider turbulent flow of an incompressible Newtonian fluid (densityρ, viscosityμ) in acircular tube (radiusR, lengthL). Provide the definition of the quantity(vnz)in terms of integral(s)over the appropriate quantities.4

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