Prediction of Flow and Heat Transfer through Stationary and Rotating Ribbed Ducts Using a Non-linear k−ε Model

Abstract

The present paper deals with the prediction of three-dimensional fluid flow and heat transfer in rib-roughened ducts of square cross-section, which are either stationary, or rotate in orthogonal mode. The main objective is to assess how a recently developed variant of a cubic non-linear k-ε model (proposed by Craft et al. Flow Turbul Combust 63:59-80, 1999) can predict three-dimensional flow and heat transfer characteristics through stationary and rotating ribbed ducts. The present paper discusses turbulent air flow and heat transfer through two different configurations, namely: (I) a stationary square duct with "in-line" normal and (II) a square duct with normal ribs in a "staggered" arrangement under stationary and rotating conditions, with the axis of rotation normal to the flow direction and parallel to the ribs. In this paper the flow and thermal predictions of the linear k-ε model (EVM) are also included, as a set of baseline predictions. The mean flow predictions show that both linear and non-linear k-ε models can successfully reproduce most of the measured data for stream-wise and cross-stream velocity components. Moreover, the non-linear model is able to produce better results for the turbulent stresses. The heat transfer predictions show that both EVM and NLEVM2, the more recent variant of the non-linear k-ε, with the algebraic length-scale correction term, overestimate the measured Nusselt numbers for both geometries examined. While the EVM with the differential length-scale correction term underestimates heat transfer levels, the Nusselt number predictions with the NLEVM2 and the 'NYP' term are in close agreements with the measured data. Comparisons with our earlier work, Iacovides 122 Flow Turbulence Combust (2009) 82:121-153 and Raisee (Int J Heat Fluid Flow, 20:320-328, 1999), show that the NLEVM2 thermal predictions are of similar quality to those of a second-moment closure.

Coriolis and buoyancy effects on heat transfer in viewpoint of field synergy principle and secondary flow intensity for maximization of internal cooling

“…They expressed that the overall deviation and difference between the leading and trailing heat transfer coefficient was less as the Rotation number was increased largely and the Nusselt number ratio tendency is near the stationary condition as Reynolds number is increased. Several CFD simulations to investigate the heat transfer augmentation versus the pressure drop on both leading and trailing surfaces of a rotating rectangular channel with radially inward and outward flow were conducted by Iacovides et al [15][16][17] Watanabe [18] Fransen [19] used RANS and LES turbulence modeling to simulate both a smooth channel and a channel equipped with skewed rib-roughening in rotation inward and outward flows. Many experimental studies by Han et al [20][21][22] and Sunden et al [23][24][25] were carried out to find out the influence of the rib configuration on the heat transfer augmentation against the pressure drop penalty.…”

“…F 2 and S refer to the second blending function and the invariant measure of the strain rate, respectively and F 2 is specified by Eq. (17).…”

Quantitative Study of Using Piloti for Passive Climate Adaptability in a Hot-Summer and Cold-Winter City in China

“…A cubic non-linear k–ε model proposed by Craft et al [ 36 ] is selected as the turbulence model for the CFD analysis. This turbulence model was originally developed to capture turbulence anisotropy by proposing a cubic relation between stress and strain, which significantly improves the predictions of three-dimensional fluid flow and heat transfer not only in and around a single object [ 36 , 37 , 38 ], but also around several objects [ 39 ]. This model has been successfully and widely used in mechanical engineering because of its high prediction accuracy.…”

Multi-objective optimization of asymmetric v-shaped ribs in a cooling channel using CFD, artificial neural networks and genetic algorithms

“…According to their results, v-shaped ribs induce stronger secondary flow which increases heat transfer. Lin et al [10], Li et al [11] and Raisee et al [12] solved the flow inside the ribbed ducts and analyzed the flow and heat transfer between flow and walls numerically.…”