Hamed Sadeghi

University of Ottawa · Department of Mechanical Engineering

Kolmogorov related the mean energy transport to both turbulent advection and molecular diffusion (K41), which, for moderate Reynolds numbers encountered under laboratory conditions, is not balanced. The main reason for this imbalance is the inhomogeneous and anisotropic large-scales, which are not sufficiently separated from the smallest dissipatio...

A novel similarity-based form is derived of the transport equation for the second-order velocity structure function of ((δq)2) along the centreline of a round turbulent jet using an equilibrium similarity analysis. This self-similar equation has the advantage of requiring less extensive measurements to calculate the inhomogeneous (decay and product...

In this paper, the effect of Reynolds number on the scaling range of the velocity spectra and structure functions along the centreline in a round turbulent jet is considered. Hot-wire measurements were taken over a range of exit Reynolds numbers (). Both axial (u) and transverse (v) energy spectra in the scaling range demonstrate considerable depar...

Experimental measurements were carried out to study the effect of flow modification near the jet exit on a turbulent round free jet. To achieve this, two different fine rings, with square cross-sections, were designed and placed very close to the jet exit (x/D = 0.03). The first ring was placed in the middle of the shear layer while the second ring...

A number of numerical simulations is carried out to study the turbulent cavitating flow through an orifice. We use two different two-fluid (consisting of two interpenetrating liquid and vapor phases) and three-fluid (consisting of three liquid, vapor, and non-condensable gas phases) cavitation models to extend our study. We use the finite-volume me...

Flows of air–water and saturated steam–water mixtures in a horizontal cylindrical vessel with a single or several cylindrical outlets (branches) were investigated computationally using the volume of fluid (VOF) method to separate the phases and the delayed detached eddy simulation (DDES) model to simulate turbulence. The time-dependent gas–liquid i...

Extensive computational fluid dynamics (CFD) simulations were conducted to study rimming flow in a partially-filled horizontally rotating cylinder. These flows are encountered in aero-engine bearing chambers which often exhibit complex two-phase flow scenarios as well as in multiple other engineering applications. A robust numerical scheme to model...

Extensive numerical simulations of isothermal air/water flow in an idealised model of the header/feeder system of a CANDU nuclear reactor were performed under conditions that are relevant to postulated loss-of-flow accidents (LOFA) and small-break loss-of-coolant accidents (SBLOCA). Following our recent work, in which the present CFD methodology wa...

New scaling laws of passive scalar with a constant mean gradient in decaying isotropic turbulence - Volume 899 - Hamed Sadeghi, Martin Oberlack

On new scaling laws in a temporally evolving turbulent plane jet using Lie symmetry analysis and direct numerical simulation – CORRIGENDUM - Volume 885 - H. Sadeghi, M. Oberlack, M. Gauding

Three-dimensional, time-dependent numerical simulations of gas-liquid flow in a multi-branch manifold (an idealised model of the header/feeder system of a CANDU nuclear reactor) were carried out using the volume of fluid approach to separate the phases and the detached eddy simulation model to simulate turbulence. Interest was focusse n the distrib...

A temporally evolving turbulent plane jet is studied both by direct numerical simulation (DNS) and Lie symmetry analysis. The DNS is based on a high-order scheme to solve the Navier-Stokes equations for an incompressible fluid. Computations were conducted at Reynolds number , where is defined based on the initial jet thickness, , and the initial ce...

The effect of finite hot-wire spatial resolution on turbulence statistics and velocity spectra in a round turbulent free jet is investigated. To quantify spatial resolution effects, measurements were taken using a nano-scale thermal anemometry probe (NSTAP) and compared to results from conventional hot-wires with sensing lengths of \(l=0.5\) and 1...

This paper focusses on recent developments in extending our theoretical understanding of round turbulent jets. It addresses equilibrium similarity and the scale-by-scale energy budget associated with the near to intermediate field of a round jet 10 ≤ x∕D ≤ 25. Hot wire data are provided for a jet with and without passive control, the latter being i...

A novel extension to the similarity-based form of the transport equation for the second-order velocity structure function of ⟨(δq)2⟩ along the jet centreline (see Danaila et al., 2004) has been obtained. This new self-similar equation has the desirable benefit of requiring less extensive measurements to calculate the inhomogeneous (decay and produc...

The flow in the near-to-intermediate field of a jet emanating from a long square pipe is investigated using hot-wire anemometry. The data include distributions of the mean and high order turbulence moments over 8000 < Re < 50 000 along the jet centreline. It is demonstrated that the far-field rates of the mean velocity decay and spread, as well as...

Purpose The primary purpose of this paper is to investigate the characteristics of the unsteady flow field in the wake of Eppler‐361 airfoil undergoing harmonic pitch oscillation in both pre‐stall and post‐stall regimes. Design/methodology/approach Experimental measurements were carried out to study the characteristics of the unsteady flow field w...

A number of experimental measurements are carried out to study the unsteady wake of a pitching Eppler-361 airfoil. The flow field in the wake was measured by a hot-wire anemometry at the downstream distance from trailing edge of 0.25 chord. All data were taken at the mean angle of attack of 2.5 deg and the reduced frequency of 0.1. The amplitude of...

The phenomena of cavitation are very important in a variety of industrial processes and engineering applications. Therefore, the simulation of cavitating flows in high-pressure devices has become a very challenging topic in the fields of computational fluid dynamics. This paper reports recent developments and application studies on computational fl...

A series of numerical investigations was carried out to study the behavior of cavitating turbulent flows in an orifice. In the present work, two different cavitation models were used for the simulation. In the first model, flow was modeled as two interpenetrating fluids (liquid and vapor), and in the second model, the working fluid was assumed to b...

An experimental investigation was carried out to study the unsteady flow field behind a sinusoidally pitching airfoil at reduced frequencies 0.091, 0.182 and 0.273. Streamwise instantaneous velocity and streamwise mean velocity in the wake were measured by hot-wire anemometer at downstream distance from trailing edge of 0.25 chord. To assess the ef...