Detached Eddy Simulation of Turbulent Flow and Heat Transfer in a Ribbed Duct

Abstract

Detached Eddy Simulation (DES) of a hydrodynamic and thermally developed turbulent flow is presented for a stationary duct with square ribs aligned normal to the main flow direction. The rib height to channel hydraulic diameter (e∕Dh) is 0.1, the rib pitch to rib height (P∕e) is 10 and the calculations have been carried out for a bulk Reynolds number of 20,000. DES calculations are carried out on a 963 grid, a 643 grid, and a 483 grid to study the effect of grid resolution. Based on the agreement with earlier LES computations, the 643 grid is observed to be suitable for the DES computation. DES and RANS calculations carried out on the 643 grid are compared to LES calculations on 963∕1283 grids and experimental measurements. The flow and heat transfer characteristics for the DES cases compare well with the LES results and the experiments. The average friction and the augmentation ratios are consistent with experimental results, predicting values within 10% of the measured quantities, at a cost lower than the LES calculations. RANS fails to capture some key features of the flow.

Detached eddy simulation of turbulent flow and heat transfer in a two-pass internal cooling duct

“…These computations have accurately captured the flow physics over geometries as complicated as an airplane Forsythe et al, 2002), car models (Kapadia et al, 2003), etc. DES computations on the fully developed flow and heat transfer in a channel with normal ribs were carried out by Viswanathan and Tafti (2004). These computations showed excellent agreement with the experiments and LES results and were an order of magnitude less expensive than LES.…”

“…This is a first such application of DES to internal flow and heat transfer and builds on previous work (Viswanathan and Tafti, 2004) which applied DES to fully developed flow and heat transfer in the same ribbed geometry. The present results are compared with LES calculations (Sewall et al, accepted for publication;Sewall and Tafti, 2005) and experiments (Rau et al, 1988;Han et al, 1988).…”

A Review of Embedded Large Eddy Simulation for Internal Flows

“…DES has been implemented with great success for a number of different applications, whilst generally performing better for flows dominated by large regions of separation. A wide range of successful studies employing DES have been reported in the literature, beyond the scope of the present work; instead the reader is encouraged to refer to the following examples [15,56,101,113]. This approach does however suffer from a couple notable issues as described by Deck [23], Tucker and Davidson [105] and Spalart et al [93] (amongst others).…”

“…In order to mitigate the high costs reported above, Viswanathan and Tafti [113] adopted DES on the same domain used by Tafti [97] achieving only a 9% deviation with respect to fine grid LES at 1 / 10th of the cost. Additionally several studies by Vishwanathan and Tafti [112,115,117], Liu et al [56] and Kubacki et al [47] successfully implemented hybrid based methods to predict the turbulent and mean flow features in stationary, rotating and roughened ribbed ducts -all documenting reasonable success.…”

Large eddy simulation for predicting turbulent heat transfer in gas turbines

“…Early research has mostly been conducted with the use of the Reynolds-averaged Navier-Stokes (RANS) method with a variety of turbulence models ranging from two-equation eddy-viscosity models such as the k-ε, k-ω SST, v 2 -f model and algebraic stress models, to full Reynolds stress closure with varying degrees of success [3][4][5][6][7][8][9][10][11][12]. In the last two decades, with increasing computational power and capacity, these efforts have transitioned to more advanced time-dependent methods such as large eddy simulations (LES) [13][14][15][16][17][18][19][20][21][22][23][24] and hybrid methods using unsteady RANS (URANS)-LES or detached eddy simulations (DES) [25][26][27][28]. It is clear from these LES investigations that the predictions capture the underlying flow physics with good accuracy, and predictions of heat transfer coefficients are consistent and repeatable over a range of geometries and conditions.…”