The main objective of this analytical study is to investigate heat transfer from tube banks in crossflow under isothermal boundary condition. For this purpose, a control volume is selected from the fourth row of a tube as a typical cell to study the heat transfer from an inline or staggered arrangement. An integral method of boundary layer analysis is employed to derive closed form expressions for the calculation of average heat transfer from the tubes of a bank, that can be used for a wide range of parameters including longitudinal pitch, transverse pitch, Reynolds and Prandtl numbers. The models for in-line and staggered arrangements are applicable for use over a wide range of parameters when determining heat transfer from tube banks.

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A new analytical model for spherical rough contacts, in the form of a set of relationships, is developed and solved numerically. It is shown that the maximum contact pressure is the parameter that specifies the contact pressure distribution. Simple correlations for calculating the maximum contact pressure and the radius of the macrocontact area as functions of the nondimensional parameters are proposed. A relationship for pressure distributions is derived where the load is higher than the critical load. A general pressure distribution is developed that covers the entire range of spherical contacts from the smooth Hertzian to the conforming rough contact. Finally, a criterion is derived to identify flat surfaces where the surface curvature has negligible effect on the contact pressure.

The MHD flow and heat transfer from water functionalized CNTs over a static/moving wedge are studied numerically. Thermal conductivity and viscosity of both single and multiple wall carbon nanotubes (CNTs) within a base fluid (water) of similar volume are investigated to determine the impact of these properties on thermofluid performance. The governing partial differential equations are converted into nonlinear, ordinary, and coupled differential equations and are solved using an implicit finite difference method with quasi-linearization techniques. The effects of volume fraction of CNTs and magnetic and wedge parameters are investigated and presented graphically. The numerical results are compared with the published data and are found to be in good agreement. It is shown that the magnetic field reduces boundary layer thickness and increases skin friction and Nusselt numbers. Due to higher density and thermal conductivity, SWCNTs offer higher skin friction and Nusselt numbers.

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