Imperial College London

DrMeissamBahlali

Faculty of EngineeringDepartment of Earth Science & Engineering

Research Associate
 
 
 
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Contact

 

m.bahlali CV

 
 
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Location

 

Royal School of Mines - 4.91Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
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6 results found

Bahlali ML, Yoo H, Favier J, Sagaut Pet al., 2021, A lattice Boltzmann direct coupling overset approach for the moving boundary problem, Physics of Fluids, Vol: 33, Pages: 1-20, ISSN: 1070-6631

We propose a new direct coupling scheme based on the overset technique to tackle moving boundary problems within the lattice Boltzmann framework. The scheme is based on the interpolation of distribution functions rather than moments, that is, macroscopic variables, and includes an additional hypothesis ensuring mass and momentum conservation at the interface nodes between fixed and moving grids. The method is assessed considering four test cases and considering both the vortical and the acoustic fields. It is shown that the direct coupling method results are in very good agreement with reference results on a configuration without any moving subdomain. Moreover, it is demonstrated that the direct coupling method provides an improvement of the accuracy of the lattice Boltzmann overset algorithm for aeroacoustics. In particular, a convected vortex test case is studied and reveals that the direct coupling approach leads to a better ability to conserve the vortex structure over time, as well as a reduction in spurious acoustic distorsions at the fixed/moving interface.

Journal article

Yoo H, Bahlali ML, Favier J, Sagaut Pet al., 2021, A hybrid recursive regularized lattice Boltzmann model with overset grids for rotating geometries, Physics of Fluids, Vol: 33, Pages: 1-19, ISSN: 1070-6631

Simulating rotating geometries in fluid flows for industrial applications remains a challenging task for general fluid solvers and in particular for the lattice Boltzmann method (LBM) due to inherent stability and accuracy problems. This work proposes an original method based on the widely used overset grids (or Chimera grids) while being integrated with a recent and optimized LBM collision operator, the hybrid recursive regularized model (HRR). The overset grids are used to actualize the rotating geometries where both the rotating and fixed meshes exist simultaneously. In the rotating mesh, the fictitious forces generated from its non-inertial rotating reference frame are taken into account by using a second order discrete forcing term. The fixed and rotating grids communicate with each other through the interpolation of the macroscopic variables. Meanwhile, the HRR collision model is selected to enhance the stability and accuracy properties of the LBM simulations by filtering out redundant higher order non-equilibrium tensors. The robustness of the overset HRR algorithm is assessed on different configurations, undergoing mid-to-high Reynolds number flows, and the method successfully demonstrates its robustness while exhibiting the second order accuracy.

Journal article

Bahlali ML, Henry C, Carissimo B, 2020, On the Well-Mixed Condition and Consistency Issues in Hybrid Eulerian/Lagrangian Stochastic Models of Dispersion, BOUNDARY-LAYER METEOROLOGY, Vol: 174, Pages: 275-296, ISSN: 0006-8314

Journal article

Lett C, Barrier N, Bahlali M, 2020, Converging approaches for modeling the dispersal of propagules in air and sea, Ecological Modelling, Vol: 415, Pages: 108858-108858, ISSN: 0304-3800

Journal article

Bahlali ML, Dupont E, Carissimo B, 2019, Atmospheric dispersion using a Lagrangian stochastic approach: Application to an idealized urban area under neutral and stable meteorological conditions, JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS, Vol: 193, ISSN: 0167-6105

Journal article

Bahlali ML, Dupont E, Carissimo B, 2019, A hybrid CFD RANS/Lagrangian approach to model atmospheric dispersion of pollutants in complex urban geometries, International Journal of Environment and Pollution, Vol: 64, Pages: 74-89, ISSN: 0957-4352

Lagrangian atmospheric dispersion models consist of tracking the trajectories of particles of pollutant emitted into the atmosphere. In this paper, the objective is to compare the Lagrangian and Eulerian dispersion models in the same computational fluid dynamics code (Code Saturne), therefore using the same wind and turbulence fields for both. The Lagrangian stochastic model used in this work is the simplified Langevin model (SLM) of Pope (1985, 2000) and pertains to the approaches referred to as probability density function methods. This model has been extensively used in turbulent combustion or multiphase flows, but to our knowledge, it has not been used in atmospheric dispersion applications. First, we show that the SLM respects the well-mixed criterion. Then, we validate the model in the case of a continuous point release with uniform mean wind speed and turbulent diffusivity. Finally, we validate the model with an experimental campaign involving a stably stratified surface layer.

Journal article

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