Akademik Veri Yönetim Sistemi
ZAMM ZEITSCHRIFT FÜR ANGEWANDTE MATHEMATIK UND MECHANIK, cilt.1, sa.1, ss.1-27, 2025 (SCI-Expanded)
Heat transfer differs in the regions where the flow is developed and develop-ing thermally. These regions can be differentiated by using the thermal entrylength. Many researchers have presented correlations to determine the thermalentry length for natural and forced convection. In this study, heat transfer in theentrance region of a concentric annuli is investigated. It is accepted that begin-ning from the inlet of annuli the flow is developed hydrodynamically and it isdeveloping thermally. Heat transfer is investigated where the internal or externalsurfaces of the annuli are at constant but different heat fluxes. The fluid velocityis assumed to be constant or radially variable. Due to thermal boundary condi-tions, one thermal boundary layer appears on the outer cylinder surface, anotheron the inner cylinder surface. The edge of two boundary layers will be adia-batic and naturally, the temperature of fluid between the two edges will be equalto free stream temperature. Transformation, Separation of Variables method,eigenvalue problem, Sturm-Liouville system, Bessel differential equation andproperties of orthogonal functions are used in solution of the problem. Exactand analytical solutions of the momentum and energy equations are presented.Velocity and temperature distributions, local Nusselt numbers and convectionheat transfer coefficients are calculated for the internal and external surfaces of annuli.