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Ebrahimi, Amin (author), Sattari, Mohammad (author), Babu, A. (author), Sood, A. (author), Römer, Gert Willem R.B.E. (author), Hermans, M.J.M. (author)Laser beam shaping offers remarkable possibilities to control and optimise process stability and tailor material properties and structure in laser-based welding and additive manufacturing. However, little is known about the influence of laser beam shaping on the complex melt-pool behaviour, solidified melt-track bead profile and...journal article 2023
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Babu, A. (author), Ebrahimi, Amin (author), Wu, K. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Additive manufacturing offers a significant potential for producing metallic parts with distinctly localised microstructures and mechanical properties, commonly known as functional grading. While functional grading is generally accomplished through compositional variations or in-situ thermo-mechanical treatments, variation of process...journal article 2023
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Tavakoli, Ali (author), Hashemi, Javad (author), Najafian, Mahyar (author), Ebrahimi, Amin (author)Solid-liquid phase transformation of a phase change material in a rectangular enclosure with corrugated fins is studied. Employing a physics-based model, the influence of fin length, thickness, and wave amplitude on the thermal and fluid flow fields is explored. Incorporating fins into thermal energy storage systems enhances the heat transfer...journal article 2023
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Ebrahimi, Amin (author), Hermans, M.J.M. (author)Laser butt welding of thin metal sheets is a widely used fusion-based joining technique in industrial manufacturing. A comprehensive understanding of the complex transport phenomena during the welding process is essential for achieving high-quality welds. In the present work, high-fidelity numerical simulations are employed to investigate the...journal article 2023
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Shariati, Vahid (author), Roohi, Ehsan (author), Ebrahimi, Amin (author)The direct simulation Monte Carlo (DSMC) method, which is a probabilistic particle-based gas kinetic simulation approach, is employed in the present work to describe the physics of rarefied gas flow in super nanoporous materials (also known as mesoporous). The simulations are performed for different material porosities (0.5≤ϕ≤0.9), Knudsen...journal article 2023
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Zhu, Mengbo (author), Roohi, Ehsan (author), Ebrahimi, Amin (author)The gas flow characteristics in lid-driven cavities are influenced by several factors, such as the cavity geometry, gas properties, and boundary conditions. In this study, the physics of heat and gas flow in cylindrical lid-driven cavities with various cross sections, including fully or partially rounded edges, is investigated through...journal article 2023
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Ebrahimi, Amin (author)The growing demand for manufactured products with complex geometries requiring advanced fusion-based manufacturing techniques emphasises the importance of process development and optimisation to reduce the risk of adverse outcomes, which is currently impeded with traditional approaches (trial and error experiments). Development, optimisation and...doctoral thesis 2022
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Ebrahimi, Amin (author), Sattari, Mohammad (author), Bremer, Scholte J.L. (author), Luckabauer, Martin (author), Römer, Gert-willem R.B.E. (author), Richardson, I.M. (author), Kleijn, C.R. (author), Hermans, M.J.M. (author)The absorptivity of a material is a major uncertainty in numerical simulations of laser welding and additive manufacturing, and its value is often calibrated through trial-and-error exercises. This adversely affects the capability of numerical simulations when predicting the process behaviour and can eventually hinder the exploitation of fully...journal article 2022
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Ebrahimi, Amin (author), Shahabi, Vahid (author), Roohi, Ehsan (author)Gas flow and heat transfer in confined geometries at micro-and nanoscales differ considerably from those at macro-scales, mainly due to nonequilibrium effects such as velocity slip and temperature jump. Nonequilibrium effects increase with a decrease in the characteristic length-scale of the fluid flow or the gas density, leading to the failure...journal article 2021
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)Internal flow behaviour and melt-pool surface oscillations during arc welding are complex and not yet fully understood. In the present work, high-fidelity numerical simulations are employed to describe the effects of welding position, sulphur concentration (60-300 ppm) and travel speed (1.25-5 mms-1) on molten metal flow dynamics in fully...journal article 2021
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Ebrahimi, Amin (author), Babu, A. (author), Kleijn, C.R. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)One of the challenges for development, qualification and optimisation of arc welding processes lies in characterising the complex melt-pool behaviour which exhibits highly non-linear responses to variations of process parameters. The present work presents a computational model to describe the melt-pool behaviour in root-pass gas metal arc...journal article 2021
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)Development, optimisation and qualification of welding and additive manufacturing procedures to date have largely been undertaken on an experimental trial and error basis, which imposes significant costs. Numerical simulations are acknowledged as a promising alternative to experiments, and can improve the understanding of the complex process...journal article 2021
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)Molten metal melt pools are characterised by highly non-linear responses, which are very sensitive to imposed boundary conditions. Temporal and spatial variations in the energy flux distribution are often neglected in numerical simulations of melt pool behaviour. Additionally, thermo-physical properties of materials are commonly changed to...journal article 2021
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Naranjani, Benyamin (author), Roohi, Ehsan (author), Ebrahimi, Amin (author)Cooling of electronic devices is one of the critical challenges that the electronics industry is facing towards sustainable development. Aiming at lowering the surface temperature of the heat sink to limit thermally induced deformations, corrugated channels and nanofluids are employed to improve the thermal and hydraulic performances of a...journal article 2020
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)The high degree of uncertainty and conflicting literature data on the value of the permeability coefficient (also known as the mushy zone constant), which aims to dampen fluid velocities in the mushy zone and suppress them in solid regions, is a critical drawback when using the fixed-grid enthalpy-porosity technique for modelling non-isothermal...journal article 2019
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Richardson, I.M. (author)Heat and fluid flow in low Prandtl number melting pools during laser processing of materials are sensitive to the prescribed boundary conditions, and the responses are highly nonlinear. Previous studies have shown that fluid flow in melt pools with surfactants can be unstable at high Marangoni numbers. In numerical simulations of molten metal...conference paper 2019
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Ebrahimi, Amin (author), Naranjani, Benyamin (author), Milani, Shayan (author), Dadras Javan, Farzad (author)Heat and fluid flow in a rectangular channel heat sink equipped with longitudinal vortex generators have been numerically investigated in the range of Reynolds numbers between 25 and 200. Aqueous solutions of carboxymethyl cellulose (CMC) with different concentrations (200–2000 ppm), which are shear-thinning non-Newtonian liquids, have been...journal article 2017
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Ebrahimi, Amin (author), Roohi, E. (author)Direct simulation Monte Carlo (DSMC) method with simplified Bernoulli trials (SBT) collision scheme has been used to study the rarefied pressure-driven nitrogen flow through diverging micro- and nanochannels. The fluid behaviours flowing between two plates with different divergence angles ranging between 0° and 17° are described at different...journal article 2017
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Ebrahimi, Amin (author), Naranjani, Benyamin (author)In this study, a flat-plate channel configured with pyramidal protrusions are numerically analysed for the first time. Simulations of laminar single-phase fluid flow and heat transfer characteristics are developed using a finite-volume approach under steady-state condition. Pure water is selected as the coolant and its thermo-physical...journal article 2016