Prediction of heat transfer coefficients in drag reducing turbulent pipe flows

A New Model for Prediction of Heat Eddy Diffusivity in Pipe Expansion Turbulent Flows

A new model to calculate heat eddy diffusivity in separating and reattaching flows based on modification of constant Prt is proposed. This modification is made using an empirical correlation between maximum Nusselt number and entrance Reynolds number. The model includes both the simplicity of Prt=0.9 assumption and the accuracy of two-equation heat-transfer models. Furthermore, an appropriate l...

Direct Numerical Simulation of Turbulent Heat Transfer in Pipe Flows with various Prandtl Numbers

The direct numerical simulation (DNS) of heat transfer in a fully developed turbulent pipe flow with for various Prandtle numbers are performed to obtain statistical quantities such as turbulent heat flux, and temperature variance. Main emphasis is placed on Prandtl number effects on turbulent heat transfer in pipe flow. Probability density functions and joint probability density functions of v...

Measurement of temperature profiles in turbulent pipe flow of polymer and surfactant drag-reducing solutions

A device was built to measure temperature profiles of turbulent pipe flows of various drag-reducing fluids. It is easy to use and reliable. We measured temperature profiles over a range of conditions leading to accurate measurements down to y+ 10, for tests carried over Reynolds numbers Re between 10 000 and 90 000. The effects of high heat fluxes and buoyancy, in particular, were quantified to...

Fluid Flow and Heat Transfer Structures of Oscillating Pipe Flows

The RANS method with Saffman’s turbulence model was employed to solve the time-dependent turbulent Navier-Stokes and energy equations for oscillating pipe flows. The method of partial sums of the Fourier series is used to analyze the harmonic velocity and temperature results. The complete structures of the oscillating pipe flows and the averaged Nusselt numbers on the tube wall are provided by ...

Convective Heat Transfer of Nanofluids Flows Through an Isothermally Heated Curved Pipe