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Jam Hans Kuipers - One of the best experts on this subject based on the ideXlab platform.
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direct numerical simulation of Fluid flow accompanied by coupled mass and heat transfer in Dense Fluid particle systems
Chemical Engineering Science, 2014Co-Authors: N Niels G Deen, Jam Hans KuipersAbstract:Abstract In this paper we report the extension of an earlier reported DNS method ( Deen et al., 2012 , Deen and Kuipers, 2013 ) based on a novel Immersed Boundary Method (IBM) which incorporates the Fluid–solid coupling at the level of the discrete field equations. The extended method is used to study coupled mass and heat transport in Dense Fluid–particle systems where the coupling arises as a consequence of an exothermal chemical reaction proceeding at the exterior surface of the particles. Following a detailed verification (using an independent numerical technique) and validation (using established empirical correlations) we apply our DNS technique to study coupled mass and heat transfer in a Dense Fluid–particle system. In addition a comparison is made with results obtained from a simple one-dimensional (1D) heterogeneous reactor model which uses empirical closures for the Fluid–particle mass and heat transfer coefficients. The main features of the complex transient temperature profiles obtained from our DNS agree quite well with the corresponding profiles obtained from the 1D heterogeneous reactor model.
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direct numerical simulation dns of mass momentum and heat transfer in Dense Fluid particle systems
Current opinion in chemical engineering, 2014Co-Authors: N Niels G Deen, Jam Hans KuipersAbstract:Direct Numerical Simulation (DNS) of complex multiphase flows is rapidly gaining attention. In this paper we explain the role of Direct Numerical Simulation (DNS) in the context of a multi-scale approach to model systems involving mass, momentum and heat transfer in Dense Fluid-particle systems. Following a brief description of the theoretical framework and the associated computational methods we present several illustrative results highlighting the power of DNS to generate detailed closures for Fluid-particle interaction. Finally, several future challenges are indicated.
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direct numerical simulation of Fluid flow and mass transfer in Dense Fluid particle systems
Industrial & Engineering Chemistry Research, 2013Co-Authors: N Niels G Deen, Jam Hans KuipersAbstract:In this paper, a novel simulation technique is presented to perform direct numerical simulation (DNS) of Fluid flow and mass transfer in Dense Fluid–particle systems. The Fluid–solid coupling is achieved via direct (i.e., implicit) incorporation of the boundary condition (with a second-order method) at the surface of the particles at the level of the discrete momentum and species conservation equations of the Fluid. A fixed (Eulerian) grid is utilized to solve the Navier–Stokes equations for the entire computational domain. Dissipative particle–particle and/or particle–wall collisions are taken into account via a hard-sphere discrete particle (DP) approach, using a three-parameter particle–particle interaction model that accounts for normal and tangential restitution, as well as tangential friction. Following the verification of our method using well-known empirical expressions for the Sherwood number, we apply our method to study Fluid–particle mass transfer in Dense multiparticle systems involving rando...
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direct numerical simulation of flow and heat transfer in Dense Fluid particle systems
Chemical Engineering Science, 2012Co-Authors: N Niels G Deen, Shl Sebastian Kriebitzsch, Martin A Van Der Hoef, Jam Hans KuipersAbstract:Abstract In this paper a novel simulation technique is presented to perform Direct Numerical Simulation (DNS) of Fluid flow and heat transfer in Dense Fluid–particle systems. The unique feature of our Fluid–solid coupling technique is the direct (i.e., implicit) incorporation of the boundary condition (with a second-order method) at the surface of the particles at the level of the discrete momentum and thermal energy equations of the Fluid. Contrary to lattice Boltzmann or other commonly used immersed boundary implementations, our method does not require using any effective diameter. A fixed (Eulerian) grid is utilized to solve the Navier–Stokes equations for the entire computational domain. Dissipative particle–particle and/or particle-wall collisions are accounted via a hard sphere discrete particle approach using a three-parameter particle–particle interaction model accounting for normal and tangential restitution and tangential friction. Following the detailed verification of the method several Dense multi-particle systems are studied in detail involving stationary arrays of particles and Fluidized particles.
K.n. Khanna - One of the best experts on this subject based on the ideXlab platform.
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Self-diffusion coefficients of Dense Fluid for a square-well Fluid
Journal of Molecular Liquids, 2007Co-Authors: Rajat Srivastava, K.n. KhannaAbstract:Self-diffusion coefficients for a Dense Fluid of particles interacting with a square-well potential employing high temperature approximation have been described. Further, the dependence of the diffusion coefficient and shear viscosity on the excess entropy have been analyzed for a square-well potential. Hence, scaling laws of diffusion coefficients and shear viscosity have been described separately for square-well Fluids.
Sorin Bastea - One of the best experts on this subject based on the ideXlab platform.
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Transport properties of Dense Fluid argon.
Physical Review E, 2003Co-Authors: Sorin BasteaAbstract:We calculate using molecular dynamics simulations the transport properties of realistically modeled Fluid argon at pressures up to $\ensuremath{\simeq}50\mathrm{GPa}$ and temperatures up to 3000 K. In this context, we provide a critique of some newer theoretical predictions for the diffusion coefficients of liquids and a discussion of the Enskog theory relevance under two different adaptations: modified Enskog theory and effective diameter Enskog theory. We also analyze a number of experimental data for the thermal conductivity of monoatomic and small diatomic Dense Fluids.
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Transport properties of Dense Fluid argon.
Physical review. E Statistical nonlinear and soft matter physics, 2003Co-Authors: Sorin BasteaAbstract:We calculate using molecular dynamics simulations the transport properties of realistically modeled Fluid argon at pressures up to approximately 50 GPa and temperatures up to 3000 K. In this context, we provide a critique of some newer theoretical predictions for the diffusion coefficients of liquids and a discussion of the Enskog theory relevance under two different adaptations: modified Enskog theory and effective diameter Enskog theory. We also analyze a number of experimental data for the thermal conductivity of monoatomic and small diatomic Dense Fluids.
Peter G Baines - One of the best experts on this subject based on the ideXlab platform.
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mixing regimes for the flow of Dense Fluid down slopes into stratified environments
Journal of Fluid Mechanics, 2005Co-Authors: Peter G BainesAbstract:Downslope flows into density-stratified environments have been observed to have the character of detraining gravity currents on small slopes, and of entraining plumes on steep slopes. In this paper, observations of flows on slopes of intermediate (20°-30°) steepness are described, and their mixing properties quantified. Both gravity-current-like and plume-like flows are observed, and an observational boundary between these two types is identified. Theoretical models for the bulk properties of these flows are presented, and their predictions are compared with the observations. A theoretical criterion is derived for the limit of applicability of the gravity-current model in terms of the Buoyancy number, the bottom slope and the bottom drag coefficient. This provides a criterion for the boundary between the plume-like and gravity-current-like flows, which is consistent with the observations. These results have implications for the modelling of downslope flows in nature, and indicate where the appropriate dynamical model may change from one type to the other.
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eddy formation by Dense flows on slopes in a rotating Fluid
Journal of Fluid Mechanics, 1998Co-Authors: Gregory F Laneserff, Peter G BainesAbstract:Properties of the flow generated by a continuous source of Dense Fluid on a slope in a rotating system are investigated with a variety of laboratory experiments. The Dense Fluid may initially flow down the slope but it turns (under the influence of rotation) to flow along the slope, and initial geostrophic adjustment gives it an anticyclonic velocity profile. Some of the Dense Fluid drains downslope in a viscous Ekman layer, which may become unstable to growing waves. Provided that the viscous draining is not too strong, cyclonic vortices form periodically in the upper layer and the Dense flow breaks up into a series of domes. Three processes may contribute to the formation of these eddies. First, initial downslope flow of the Dense current may stretch columns of ambient Fluid by the ‘Taylor column’ process (which we term ‘capture’). Secondly, the initial geostrophic adjustment implies lower-layer collapse which may stretch the Fluid column, and thirdly, viscous drainage will progressively stretch and spin up a captured water column. Overall this last process may be the most significant, but viscous drainage has contradictory effects, in that it progressively removes Dense lower-layer Fluid which terminates the process when the layer thickness approaches that of the Ekman layer. The eddies produced propagate along the slope owing to the combined effects of buoyancy–Coriolis balance and ‘beta-gyres’. This removes Fluid from the vicinity of the source and causes the cycle to repeat. The vorticity of the upper-layer cyclones increases linearly with Γ = L α/ D (where L is the Rossby deformation radius, α the bottom slope and D the total depth), reaching approximately 2 f in the experiments presented here. The frequency at which the eddy/dome structures are produced also increases with Γ , while the speed at which the structures propagate along the slope is reduced by viscous effects. The flow of Dense Fluid on slopes is a very important part of the global ocean circulation system and the implications of the laboratory experiments for oceanographic flows are discussed.
N Niels G Deen - One of the best experts on this subject based on the ideXlab platform.
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direct numerical simulation of Fluid flow accompanied by coupled mass and heat transfer in Dense Fluid particle systems
Chemical Engineering Science, 2014Co-Authors: N Niels G Deen, Jam Hans KuipersAbstract:Abstract In this paper we report the extension of an earlier reported DNS method ( Deen et al., 2012 , Deen and Kuipers, 2013 ) based on a novel Immersed Boundary Method (IBM) which incorporates the Fluid–solid coupling at the level of the discrete field equations. The extended method is used to study coupled mass and heat transport in Dense Fluid–particle systems where the coupling arises as a consequence of an exothermal chemical reaction proceeding at the exterior surface of the particles. Following a detailed verification (using an independent numerical technique) and validation (using established empirical correlations) we apply our DNS technique to study coupled mass and heat transfer in a Dense Fluid–particle system. In addition a comparison is made with results obtained from a simple one-dimensional (1D) heterogeneous reactor model which uses empirical closures for the Fluid–particle mass and heat transfer coefficients. The main features of the complex transient temperature profiles obtained from our DNS agree quite well with the corresponding profiles obtained from the 1D heterogeneous reactor model.
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direct numerical simulation dns of mass momentum and heat transfer in Dense Fluid particle systems
Current opinion in chemical engineering, 2014Co-Authors: N Niels G Deen, Jam Hans KuipersAbstract:Direct Numerical Simulation (DNS) of complex multiphase flows is rapidly gaining attention. In this paper we explain the role of Direct Numerical Simulation (DNS) in the context of a multi-scale approach to model systems involving mass, momentum and heat transfer in Dense Fluid-particle systems. Following a brief description of the theoretical framework and the associated computational methods we present several illustrative results highlighting the power of DNS to generate detailed closures for Fluid-particle interaction. Finally, several future challenges are indicated.
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direct numerical simulation of Fluid flow and mass transfer in Dense Fluid particle systems
Industrial & Engineering Chemistry Research, 2013Co-Authors: N Niels G Deen, Jam Hans KuipersAbstract:In this paper, a novel simulation technique is presented to perform direct numerical simulation (DNS) of Fluid flow and mass transfer in Dense Fluid–particle systems. The Fluid–solid coupling is achieved via direct (i.e., implicit) incorporation of the boundary condition (with a second-order method) at the surface of the particles at the level of the discrete momentum and species conservation equations of the Fluid. A fixed (Eulerian) grid is utilized to solve the Navier–Stokes equations for the entire computational domain. Dissipative particle–particle and/or particle–wall collisions are taken into account via a hard-sphere discrete particle (DP) approach, using a three-parameter particle–particle interaction model that accounts for normal and tangential restitution, as well as tangential friction. Following the verification of our method using well-known empirical expressions for the Sherwood number, we apply our method to study Fluid–particle mass transfer in Dense multiparticle systems involving rando...
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direct numerical simulation of flow and heat transfer in Dense Fluid particle systems
Chemical Engineering Science, 2012Co-Authors: N Niels G Deen, Shl Sebastian Kriebitzsch, Martin A Van Der Hoef, Jam Hans KuipersAbstract:Abstract In this paper a novel simulation technique is presented to perform Direct Numerical Simulation (DNS) of Fluid flow and heat transfer in Dense Fluid–particle systems. The unique feature of our Fluid–solid coupling technique is the direct (i.e., implicit) incorporation of the boundary condition (with a second-order method) at the surface of the particles at the level of the discrete momentum and thermal energy equations of the Fluid. Contrary to lattice Boltzmann or other commonly used immersed boundary implementations, our method does not require using any effective diameter. A fixed (Eulerian) grid is utilized to solve the Navier–Stokes equations for the entire computational domain. Dissipative particle–particle and/or particle-wall collisions are accounted via a hard sphere discrete particle approach using a three-parameter particle–particle interaction model accounting for normal and tangential restitution and tangential friction. Following the detailed verification of the method several Dense multi-particle systems are studied in detail involving stationary arrays of particles and Fluidized particles.