Searched for: subject%3A%22Direct%255C+numerical%255C+simulations%22
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Shajahan, M.T. (author)
Dense suspension flows, both in the natural environment and industrial settings, are complex phenomena with significant implications. From rivers shaping landscapes to industrial processes involving slurry transport, these flows hold a prominent position in numerous sectors. This thesis delves into a specific facet of these intricate flows:...
doctoral thesis 2024
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Tosto, F. (author)
The vast majority of energy conversion systems currently makes use of fossil fuels, whose combustion generates harmful greenhouse gases. Transitioning to renewable energy sources is thus paramount to limiting the environmental impact of human activities on the climate. In this regard, the harvesting of wasted thermal energy constitutes a...
doctoral thesis 2023
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Singh, Ankit (author)
Amidst the rise in fossil fuel consumption and the global energy crisis, there is a growing demand for clean, environmentally friendly, and sustainable energy solutions in industrial processes. One promising approach is to substitute conventional working fluids in power cycles with supercritical fluids. Over recent decades, substantial research...
master thesis 2023
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Chakraborty, Aneek (author)
Thermal convection is a phenomenon seen in almost all facets of life, ranging from planetary convection to ocean currents and convection inside the Earth. The physics of thermal convection complicates when a porous wall layer is present. Flow over urban canopies, forest canopies or flow in underground aquifers are classic examples where thermal...
master thesis 2023
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Kotturshettar, Sanath (author)
Stratified turbulent flows abound in environmental and industrial settings. Examples are atmospheric boundary layer flows, the transport of nutrients and organisms and the mixing of heat and salinity in the oceans, fluid flow in heat exchangers, and the transport of reactants and products in chemical reactions. These examples and many others...
master thesis 2023
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Tosto, F. (author), Wheeler, Andrew (author), Pini, M. (author)
In this work, we investigate the sources of dissipation in adiabatic boundary layers of non-ideal compressible fluid flows. Direct numerical simulations of transitional, zero-pressure gradient boundary layers are performed with an in-house solver considering two fluids characterized by different complexity of the fluid molecules, namely air...
book chapter 2023
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Shahzad, H. (author), Hickel, S. (author), Modesti, D. (author)
We perform direct numerical simulations of turbulent flow at friction Reynolds number Re<sub>τ</sub>≈ 500 - 2000 grazing over perforates plates with moderate viscous-scaled orifice diameter d<sup>+</sup>≈ 40 - 160 and analyse the relation between permeability and added drag. Unlike previous studies of turbulent flows over permeable surfaces,...
journal article 2022
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Shin, H. H. (author), Portela, L. (author), Schaerer, C. E. (author), Mangiavacchi, N. (author)
The dynamics of suspended sediment transport in horizontal open channel flow is analysed using point-particle one-way coupling Direct Numerical Simulations (DNS), with a virtual wall as a simple particle resuspension model. In sediment transport, the bed-load is dominated by the inter-particle interactions, but the suspended sediments are...
journal article 2022
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Doan, Nguyen Anh Khoa (author)
In this chapter, the research dedicated to moderate or intense low-oxygen dilution (MILD) combustion (also called flameless combustion) that relied on direct numerical simulations (DNS) is summarized. In particular, the various DNS carried out are detailed and three different configurations are considered: the autoigniting mixing layer...
book chapter 2022
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Jigjid, K. (author), Minamoto, Yuki (author), Doan, Nguyen Anh Khoa (author), Tanahashi, Mamoru (author)
A neural network (NN) aided model is proposed for the filtered reaction rate in moderate or intense low-oxygen dilution (MILD) combustion. The framework of the present model is based on the partially stirred reactor (PaSR) approach, and the fraction of the reactive structure appearing in the PaSR is predicted using different NN's, to consider...
journal article 2022
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Bernardini, Matteo (author), Modesti, D. (author), Salvadore, Francesco (author), Pirozzoli, Sergio (author)
We present STREAmS, an in-house high-fidelity solver for direct numerical simulations (DNS) of canonical compressible wall-bounded flows, namely turbulent plane channel, zero-pressure gradient turbulent boundary layer and supersonic oblique shock-wave/boundary layer interaction. The solver incorporates state-of-the-art numerical algorithms,...
journal article 2021
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van Hooft, J.A. (author)
The scalar front generated by the horizontal self advection of a dipolar vortex through a mod-est scalar gradient is investigated. This physical scenario is an idealization of the emergenceof strong temperature ramps in the stable atmospheric boundary layer. The proposed mecha-nism is discussed and a two-dimensional analogy is studied in depth...
journal article 2020
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Pacha Sanjeevi, S.K. (author)
This work focuses on creating a recipe for parametrizing flow around assemblies of non-spherical particles. A multi-relaxation time lattice Boltzmann method (MRT-LBM) is used to simulate the flow. The research focuses on 3 different developments. First, different boundary conditions available in the literature for LBM are tested to identify the...
doctoral thesis 2019
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Altenburg, Luuk (author)
Sedimentation of particle suspensions is a relevant process to a variety of applications, such as the reclamation of land and chemical engineering systems. Direct numerical simulations of the settling of a single, two and multiple solid spheres under gravity in a square duct have been performed. The simulations involve 4 different Galileo...
master thesis 2019
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Brändle de Motta, J. C. (author), Simões Costa, P. (author), Derksen, J. J. (author), Peng, C. (author), Wang, L. P. (author), Breugem, W.P. (author), Estivalezes, J. L. (author), Vincent, S. (author), Climent, E. (author), Fede, P. (author), Barbaresco, P. (author), Renon, N. (author)
During the last decade, many approaches for resolved-particle simulation (RPS) have been developed for numerical studies of finite-size particle-laden turbulent flows. In this paper, three RPS approaches are compared for a particle-laden decaying turbulence case. These methods are, the Volume-of-Fluid Lagrangian method, based on the viscosity...
journal article 2019
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Peeters, J.W.R. (author), Sandham, N. D. (author)
It is well known that rough surfaces affect turbulent flows significantly. How such surfaces affect turbulent heat transfer is less well understood. To gain more insight, we have performed a series of direct numerical simulations of turbulent heat transfer in a channel flow with grit-blasted surfaces. An immersed boundary method is used to...
journal article 2019
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Mandyam Chakravarthy, Akshar (author)
Laminar-turbulent transition (LTT) is the process through which smooth laminar flow transits into chaotic turbulent flow. Investigation of the paths taken to transit into turbulence is a front-runner among other methods followed to characterise turbulent flows. This is of particular importance in aerospace and energy industries for the design of...
master thesis 2018
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van Hooft, J.A. (author), Popinet, Stéphane (author), van Heerwaarden, Chiel C. (author), van der Linden, S.J.A. (author), de Roode, S.R. (author), van de Wiel, B.J.H. (author)
We present a proof-of-concept for the adaptive mesh refinement method applied to atmospheric boundary-layer simulations. Such a method may form an attractive alternative to static grids for studies on atmospheric flows that have a high degree of scale separation in space and/or time. Examples include the diurnal cycle and a convective...
journal article 2018
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Patel, A. (author)
Wall-bounded turbulence involving mixing of scalars, such as temperature or concentration fields, play an important role in many engineering applications. In applications with large temperature or concentration differences, the variation of scalar dependent thermos physical properties can be strong. In such cases the strong coupling between...
doctoral thesis 2017
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Benschop, H.O.G. (author), Breugem, W.P. (author)
A bird-feather-inspired herringbone riblet texture was investigated for turbulent drag reduction. The texture consists of blade riblets in a converging/diverging or herringbone pattern with spanwise wavelength Λf. The aim is to quantify the drag change for this texture as compared to a smooth wall and to study the underlying mechanisms. To that...
journal article 2017
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