M. S. Shadloo | INSA ROUEN (original) (raw)

Papers by M. S. Shadloo

Proceedings of the 6th World Congress on Momentum, Heat and Mass Transfer, 2021

Physics of Fluids, 2020

This work studies the development of a thermal boundary layer during the laminar-to-turbulent tra... more This work studies the development of a thermal boundary layer during the laminar-to-turbulent transition process over a concave surface. Direct numerical simulations are performed where the temperature variable is treated as a passive scalar. The laminar flow is perturbed with wall-roughness elements that are able to produce centrifugal instabilities in the form of Gortler vortices with a maximum growth rate. It is found that Gortler vortices are able to greatly modify the surface heat-transfer by generating a spanwise periodic distribution of temperature. Similar to the Gortler momentum boundary layer, elongated mushroom-like structures of low-temperature are generated in the upwash region, whereas in the downwash region, the thermal boundary layer is compressed. Consequently, temperature gradients are increased and decreased in the downwash and upwash regions, respectively, thereby generating an overall enhancement of the heat-transfer rate of ∼400% for the investigated Prandtl numbers (Pr = 0.72, Pr = 1, and Pr = 7.07). This enhancement surpasses the turbulent heat-transfer values during the transitional region, characterized by the development of secondary instabilities. However, downstream, the heat-transfer rate decays to the typical turbulent values. Streamwise evolution of several thermal quantities such as temperature wall-normal distribution, thermal boundary layer thickness, and Stanton number is reported in different regions encountered in the transition process, namely, linear, nonlinear, transition, and fully turbulent regions. These quantities are reported locally at upwash and downwash regions, where they present minima and maxima, as well as globally as spanwise-averaged quantities. Furthermore, it is found that the Reynolds analogy between streamwise-momentum and heat-transfer holds true throughout the whole transition process for the Pr = 1 case. Moreover, the turbulent thermal boundary layer over a concave surface is analyzed in detail for the first time. The viscous sub-layer and the log-law region are described for each investigated Pr. Besides, the root-mean-squared temperature fluctuations are computed, finding that its wall-normal distribution exhibits a higher peak when Pr is increased.

Numerical Heat Transfer, Part A: Applications, 2018

Heat and Mass Transfer, 2018

Physics of Fluids, 2014

ABSTRACT This work reports a numerical investigation of shock focusing phenomena over con-cave su... more ABSTRACT This work reports a numerical investigation of shock focusing phenomena over con-cave surfaces. The study focuses on the effects of Reynolds and Mach numbers on the detailed behavior of flow features related to shear-layer instabilities and jet formation in the post-shock region. Computations are done for four incident-shock Mach numbers covering subsonic and transonic flow regimes and a wide range of Reynolds numbers. The simulations reveal a number of interesting wave features starting from early stage of shock interaction and transition from inverse-Mach re-flection to transitioned regular reflection followed by very complex flow patterns at focusing and post focusing stages. Different subsequent flow characteristics de-velop as a result of multiple shock/shear layer interactions. During the later stage of the flow interaction, a formation of two opposing jets is predicted by the simula-tion in accordance with the experiments. It is shown that the formation of primary opposing jets as well as the development of Kelvin-Helmholtz instabilities can be hindered for low Mach and Reynolds numbers. However, for high flow regimes a second pair of opposing jets appears and develops far from the wall, exhibiting sim-ilar features as the primary pair of opposing jets at moderate Mach numbers. Two new bifurcations in flow patterns are observed at this stage which promote further development of vortex structures and shear-layer rollup. C 2014 AIP Publishing LLC.

International Journal for Numerical Methods in Engineering, 2011

Computational Mechanics, 2012

Computational Mechanics, 2013

A steady state and two-dimensional laminar free convection heat transfer in a partitioned cavity ... more A steady state and two-dimensional laminar free convection heat transfer in a partitioned cavity with horizontal adiabatic and isothermal side walls is investigated using both experimental and numerical approaches. The experiments and numerical simulations are carried out using a Mach-Zehnder interferometer and a finite volume code, respectively. A horizontal and adiabatic partition, with angle of θ is adjusted such that it separates the cavity into two identical parts. Effects of this angel as well as Rayleigh number on the heat transfer from the side-heated walls are investigated in this study. The results are performed for the various Rayleigh numbers over the cavity side length, and partition angles ranging from 1.5 × 10 5 to 4.5 × 10 5 , and 0 ° to 90 ° , respectively. The experimental verification of natural convective flow physics has been done by using FLUENT software. For a given adiabatic partition angle, the results show that the average Nusselt number and consequently the heat transfer enhance as the Rayleigh number increases. However, for a given Rayleigh number the maximum and the minimum heat transfer occurs at θ = 45 ° and θ = 90 ° , respectively. Two responsible mechanisms for this behavior, namely blockage ratio and partition orientation, are identified. These effects are explained by numerical velocity vectors and experimental temperatures contours. Based on the experimental data, a new correlation that fairly represents the average Nusselt number of the heated walls as functions of Rayleigh number and the angel of θ for the aforementioned ranges of data is proposed.

Please cite this article in press as: M.Y.A. Jamalabadi, et al., Effect of injection angle, densi... more Please cite this article in press as: M.Y.A. Jamalabadi, et al., Effect of injection angle, density ratio, and viscosity on droplet formation in a microfluidic T-junction, Theoretical & Applied Mechanics Letters (2017), http://dx.

In this paper, a three-dimensional lattice Boltzmann model is proposed to simulate pool-boiling p... more In this paper, a three-dimensional lattice Boltzmann model is proposed to simulate pool-boiling phenomena at high-density ratios. The present model is able to predict the temperature field inside the bubble. The three-dimensional multiphase model is validated against the analytical solution of evaporation d 2 law problem and Laplace's law. In addition, effects of different parameters including, Jacob number, gravitational acceleration (g) and surface tension (σ) on bubble departure diameter are presented for further validation. The bubble departure diameter is found to be proportional to g −0.354 and σ 0.5 , and has a linear relation with Jacob number. These results are more consistent with previous experimental correlations when compared with available lattice Boltzmann literature. Furthermore, the dynamic behavior of multiple bubble formation sites such as micro convection and vortex ring mechanism are presented to show the capability of presented model for capturing more complex physical phenomena. To sum up, the proposed three-dimensional lattice Boltzmann model is feasible and accurate for numerical simulations of pool boiling.

In this paper, numerical analysis of the pool boiling heat transfer on isothermal elliptical tube... more In this paper, numerical analysis of the pool boiling heat transfer on isothermal elliptical tubes with different aspect ratios at saturated condition is presented. Bubbles' tip velocities and positions, interfacial topological changes as well as convection heat fluxes of five different cases are presented for wide ranges of wall temperatures. Both time-averaged and dynamic behaviors of flow physics and heat transfer are investigated. The departure time of the first bubble, its time-dependent and averaged velocities, and heat fluxes are obtained. Finally, a novel correlation is presented for the Nusselt number that accounts for the elliptical tubes' diameter and aspect ratio.

Smoothed Particle Hydrodynamics (SPH) is a relatively new meshless numerical approach which has a... more Smoothed Particle Hydrodynamics (SPH) is a relatively new meshless numerical approach which has attracted significant attention in the last two decades. Compared with the conventional mesh-based computational fluid dynamics (CFD) methods, the SPH approach exhibits some unique advantages in mod-eling multiphysic flows and associated transport phenomena due to its capabilities of handling complex boundary evolution as well as modeling complicated physics in a relatively simple manner. On the other hand, as SPH is still a developing CFD method, it is crucial to identify its advantages and limitations in modeling realistic multiphysic flow problems of real life and of industrial interest. Toward this end, this work aims at summarizing the motivations behind utilizing the SPH method in an industrial context, making the state-of-the-art of the present application of this method to industrial problems, as well as deriving general conclusions regarding its assets and limitations and stressing the remaining challenges in order to make it an hand-on computational tool.

International Journal of Heat and Fluid Flow, 2015

ABSTRACT Direct numerical simulations (DNS) of supersonic turbulent boundary layers (STBL) over a... more ABSTRACT Direct numerical simulations (DNS) of supersonic turbulent boundary layers (STBL) over adiabatic and isothermal walls are performed to investigate the effects of wall heat transfer on turbulent statistics and near wall behaviors. Four different cases of adiabatic, quasi-adiabatic, and uniform hot and cold wall temperatures are considered. Based on the analysis of the current database, it is observed that even though the turbulent Mach number is below 0.3, the wall heat transfer modifies the behavior of near-wall turbulence. These modifications are investigated and identified using both instantaneous fields (i.e. scatter plots) and mean quantities. Morkovin’s hypothesis for compressible turbulent flows is found to be valid for neither heated nor cooled case. It is further uncovered that although some near-wall asymptotic behaviors change upon using weak or strong adiabatic walls, respectively denote the isothermal and iso-flux walls, basic turbulent statistics are not affected by the thermal boundary condition itself. We also show that among different definition of Reynolds number used in STBL, the Reynolds number based on the friction velocity has some advantages data comparison regarding the first and second order statistical moments. More in depth analyses are also performed using the balance equation for turbulent kinetic energy (TKE) budget, as well as the dissipation rate. It is found that the dilatational to solenoidal dissipation ratio increases/decreases when heating/cooling the walls. The DNS of the current STBLs are available online for the community.