Turbulent heat transfer in a square duct

The fundamental role of fluid dynamic analyses in the design of the solid EU Test Blanket Module

“…The wall adjacent cell thickness values in the FW, CAP, SGs and bypass chunks have been set in order to keep everywhere the dimensionless wall distance y+ below 300. The turbulence model adopted is the SST k-ω: as discussed in [17] the fluid dynamic numerical simulations of turbulent complex flows in square ducts should not use the traditional eddy-diffusivity concepts too easily. Indeed k-ω and k-ε turbulence models have been tested as well: for the geometry of the MF chambers, characterized by a square cross section with a dimension one order of magnitude larger than the other, SST k-ω turbulence model results definitely to be the most robust (SST k-ω turbulence model has been strongly recommended as well by CFD developers in case of the MF chamber geometry).…”

Forced Turbulent Heat Convection in a Rectangular Duct with Non-Uniform Wall Temperature

“…The predicted distributions of the friction coefficient (NLEVM and RSM) and Nusselt number (SED and GGDH) dependence on Reynolds number for fully developed flow and heat transfer in a square duct is shown in Figure 3 TTTT  with fluid air and Re=65000 (Hirota [15]) are shown, the figure 4(b) shows the variation of the temperature profile with non-uniform wall Temperature: south=400K, north=373K, east=393K, west=353K; presented as Case I. Re (x10 4 ) In the doctoral thesis Garcia (1996) was analyzed the laminar flow coupled to the conduction and radiation in rectangular ducts and concluded that as increases the aspect ratio, the Nusselt number found in the coupling, differs from that found for ducts with In the present study, the variations of the average Nusselt number for a square duct and different cases analyzed (uniform and non uniform temperature in the perimeter) are minimal.…”

“…Recently, Qin and Fletcher [1] showed that Prandtl's secondary flow of the second kind has a significant effect in the transport of heat and momentum, as revealed by the recent Large Eddy Simulation (LES) technique. Several experimental and numerical studies have been conducted on turbulent flow though of non-circular ducts: Nikuradse [2]; Gessner and Emery [3]; Gessner and Po [4]; Melling and Whitelaw [5]; Nakayama et al [6]; Myon and Kobayashi [7]; Assato [8]; Assato and De Lemos [9]; Home et al [10]; Luo et al [11]; Ergin et al [12] Launder and Ying [13]; Emery et al [14]; Hirota et al [15]; Rokni [16]; Hongxing [17]; Yang and Hwang [18]; Park [19];Zhang et al [20]; Zheng et al [21]; Su and Da Silva Neto [22]; Saidi and Sundén [23]; Rokni [24]; Valencia [25]; Sharatchandra and Rhode [26]; Campo et al [27]; Rokni and Sundén [28]; Yang and Ebadian [29] and others. The Melling and Whitelaw´s [5] experimental work shows characteristics of turbulent flow in a rectangular duct where they have been used a laser-Doppler anemometer in which report the axial development mean velocity, secondary mean velocity, etc.…”

“…Nakayama et al [6] show the analysis of the fully developed flow field in rectangular and trapezoidal cross-section ducts; finite difference method was implemented and the model of Launder and Ying [13] has been used. On the other hand, Hirota et al [15] present an experimental work in turbulent heat transfer in square ducts; they show details of turbulent flows and temperature fields. Likewise, Rokni [16] carried out a comparison of four different turbulence models for predicting the turbulent Reynolds stresses, and three turbulent heat flux models for square ducts.…”

The influence of wall heating on the flow structure in the near-wall region

“…They also observed that unstable stratification has no effect on the temperature fluctuation in the inner region but the magnitude of temperature fluctuations decreased with the Richardson number in the outer region. Hirota et al (1997) measured velocity and temperature in a square duct using hot-wire probes for a single Reynolds number for fully turbulent flow under isothermal heating condition in the plane perpendicular to the flow. They observed that the turbulent heat fluxes in the streamwise direction are distorted towards the duct corner.…”