Direct numerical simulation of turbulent flow in a square duct

Abstract

A direct numerical simulation of a fully developed, low-Reynolds-number turbulent flow in a square duct is presented. The numerical scheme employs a time-splitting method to integrate the three-dimensional, incompressible Navier-Stokes equations using spectral/high-order finite-difference discretization on a staggered mesh; the nonlinear terms are represented by fifth-order upwind-biased finite differences. The unsteady flow field was simulated at a Reynolds number of 600 based on the mean friction velocity and the duct width, using 96 × 101 × 101 grid points. Turbulence statistics from the fully developed turbulent field are compared with existing experimental and numerical square duct data, providing good qualitative agreement. Results from the present study furnish the details of the corner effects and near-wall effects in this complex turbulent flow field; also included is a detailed description of the terms in the Reynolds-averaged streamwise momentum and vorticity equations. Mechanisms responsible for the generation of the stress-driven secondary flow are studied by quadrant analysis and by analysing the instantaneous turbulence structures. It is demonstrated that the mean secondary flow pattern, the distorted isotachs and the anisotropic Reynolds stress distribution can be explained by the preferred location of an ejection structure near the corner and the interaction between bursts from the two intersecting walls. Corner effects are also manifested in the behaviour of the pressure-strain and velocity-pressure gradient correlations.

Numerical study of forced turbulent heat convection in a straight square duct

“…The recent contributions to computational fluid dynamics were those using large eddy simulation(LES) [13][14][15][16][17][18][19] and direct numerical simulation (DNS) [20][21][22][23]. In particular, Vázquez and Métais [15] predicted the asymmetrical wall heating and the fluid compressibility effects.…”

Towards a Nonlinear Eddy-Viscosity Model Based on Elliptic Relaxation

“…The predominant effect of this secondary motion is the induced transfer of streamwise momentum towards the corner; the isolevels of the streamwise mean velocity becomes distorted. Figure 4 shows a detailed comparison of the predicted mean velocity field with the DNS data reported by Huser and Biringen [28] at Re * ≡ 2hu * /ν = 600. Here 2h is the duct height (or width) and u * is the averaged wall friction velocity.…”

“…However, since A varies according to (28), the internal consistency constraint can only be approximately fulfilled within the flow field. With α 0 = 1, (28) becomes…”

Prediction of air-side particulate fouling of HVAC&R heat exchangers

“…Turbulence causes large deposition fractions for large particle sizes, and the extension of the analysis of deposition due to turbulence to three dimensions has a measureable influence on the total deposition fraction predicted. Turbulence statistics were reported by Gavrilakis [29] and Huser and Biringen [30] in all directions, and provided the numerical data necessary to perform this analysis. Regression curves were fitted to reported turbulence statistics such as primary and secondary velocity profiles, rms values of turbulent fluctuation velocities in all directions, and Reynolds stress profiles in all directions.…”