CTTC - Centre Tecnològic de la Transferència de Calor
http://hdl.handle.net/2117/3190
Sat, 18 Nov 2017 06:44:13 GMT2017-11-18T06:44:13ZStudy of stochastic models for subgrid dispersion in Lagrangian-Eulerian formulation
http://hdl.handle.net/2117/110057
Study of stochastic models for subgrid dispersion in Lagrangian-Eulerian formulation
Muela Castro, Jordi; Lehmkuhl Barba, Oriol; Oliva Llena, Asensio
Dispersed multiphase turbulent flows are present in many industrial and commercial applications like internal combustion engines, turbofans, dispersion of contaminants, steam turbines, etc. Therefore, there is a clear interest in the development of models and numerical tools capable of performing detailed and reliable simulations about these kinds of flows. Most numerical investigations of dispersed flows use a Lagrangian-Eulerian formulation, and therefore the present work is developed under this framework.
Mon, 06 Nov 2017 17:04:40 GMThttp://hdl.handle.net/2117/1100572017-11-06T17:04:40ZMuela Castro, JordiLehmkuhl Barba, OriolOliva Llena, AsensioDispersed multiphase turbulent flows are present in many industrial and commercial applications like internal combustion engines, turbofans, dispersion of contaminants, steam turbines, etc. Therefore, there is a clear interest in the development of models and numerical tools capable of performing detailed and reliable simulations about these kinds of flows. Most numerical investigations of dispersed flows use a Lagrangian-Eulerian formulation, and therefore the present work is developed under this framework.Flow and heat transfer in a wall-bounded pin matrix
http://hdl.handle.net/2117/109336
Flow and heat transfer in a wall-bounded pin matrix
Paniagua Sánchez, Leslye; Oliet Casasayas, Carles; Lehmkuhl Barba, Oriol; Pérez Segarra, Carlos David
Fri, 27 Oct 2017 13:43:43 GMThttp://hdl.handle.net/2117/1093362017-10-27T13:43:43ZPaniagua Sánchez, LeslyeOliet Casasayas, CarlesLehmkuhl Barba, OriolPérez Segarra, Carlos DavidNumerical modelling of the phase change material heat accumulator under fast transient gasification conditions in a low thrust cryogenic propulsion (LTCP) system
http://hdl.handle.net/2117/109333
Numerical modelling of the phase change material heat accumulator under fast transient gasification conditions in a low thrust cryogenic propulsion (LTCP) system
Castro González, Jesús; Galione Klot, Pedro Andrés; Morales Ruiz, Juan José; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Pérez Segarra, Carlos David; Oliva Llena, Asensio
The study of one of the components, the heat accumulator, of Low Thrust Cryogenic Propulsion systems (LTCP),
is of scientific interest in the framework of ISP-1 project [1]. This device stores thermal energy from the fuel cell
that provides electrical energy to the whole system. This thermal energy is employed for the pressurization of the
propellant tanks. Two different types of heat accumulators are present in the LTCP system: the High Temperature
Accumulator (HTA) and the Low Temperature Accumulator (LTA). A numerical model is being developed [2] in
order to predict the thermal behavior of the LTA and having a tool for its design in the next future. Experimental
results of ISP-1 partners of DLR are being used for the validation [3], [4].
Fri, 27 Oct 2017 13:16:24 GMThttp://hdl.handle.net/2117/1093332017-10-27T13:16:24ZCastro González, JesúsGalione Klot, Pedro AndrésMorales Ruiz, Juan JoséLehmkuhl Barba, OriolRigola Serrano, JoaquimPérez Segarra, Carlos DavidOliva Llena, AsensioThe study of one of the components, the heat accumulator, of Low Thrust Cryogenic Propulsion systems (LTCP),
is of scientific interest in the framework of ISP-1 project [1]. This device stores thermal energy from the fuel cell
that provides electrical energy to the whole system. This thermal energy is employed for the pressurization of the
propellant tanks. Two different types of heat accumulators are present in the LTCP system: the High Temperature
Accumulator (HTA) and the Low Temperature Accumulator (LTA). A numerical model is being developed [2] in
order to predict the thermal behavior of the LTA and having a tool for its design in the next future. Experimental
results of ISP-1 partners of DLR are being used for the validation [3], [4].Building proper invariants for large eddy simulation
http://hdl.handle.net/2117/109217
Building proper invariants for large eddy simulation
Trias Miquel, Francesc Xavier; Folch, David; Gorobets, Andrei; Oliva Llena, Asensio
Wed, 25 Oct 2017 16:32:58 GMThttp://hdl.handle.net/2117/1092172017-10-25T16:32:58ZTrias Miquel, Francesc XavierFolch, DavidGorobets, AndreiOliva Llena, AsensioNumerical simulation of incompressible two phase flows by conservative level set method
http://hdl.handle.net/2117/109210
Numerical simulation of incompressible two phase flows by conservative level set method
Balcázar Arciniega, Néstor; Jofre Cruanyes, Lluís; Lehmkuhl Barba, Oriol; Rigola Serrano, Joaquim; Castro González, Jesús
A numerical formulation for the Conservative
Level-Set Method of Olsson and Kreiss is
implemented using the finite volume approach. Both
convective term of the interface advection equation
and compression term of the reinitialization equation
are discretized by the first order upwind plus flux
limiter scheme. Time integration is solved by the
TVD Third Order Runge Kutta method, whereas
gradients are computed by the linear Least-Squares
approach. The method is tested computing moving
interfaces with external velocity fields on unstructured
meshes.
Additionally, Level-Set method was coupled
to a variable density Navier-Stokes solver for
incompressible flow TERMOFLUIDS. Physical
properties are assumed to vary smoothly in a
narrow band around the interface to avoid numerical
instabilities. Pressure velocity coupling is solved using
a two step projection method where in the first step the
convection, diffusion and source terms are computed
explicitily using the Adams-Bashforth time integration.
In the second step the velocity is corrected by adding
the gradient of the pressure variable. Numerical
solution of pressure Poisson equation is calculated with
an efficient preconditioned conjugate gradient solver.
Mass conservation and convergence properties of the
model are investigated for cases with large density
and viscosity ratios. For the purpose of validation,
numerical results are compared with numerical and
experimental data for standard benchmark problems.
Wed, 25 Oct 2017 14:54:50 GMThttp://hdl.handle.net/2117/1092102017-10-25T14:54:50ZBalcázar Arciniega, NéstorJofre Cruanyes, LluísLehmkuhl Barba, OriolRigola Serrano, JoaquimCastro González, JesúsA numerical formulation for the Conservative
Level-Set Method of Olsson and Kreiss is
implemented using the finite volume approach. Both
convective term of the interface advection equation
and compression term of the reinitialization equation
are discretized by the first order upwind plus flux
limiter scheme. Time integration is solved by the
TVD Third Order Runge Kutta method, whereas
gradients are computed by the linear Least-Squares
approach. The method is tested computing moving
interfaces with external velocity fields on unstructured
meshes.
Additionally, Level-Set method was coupled
to a variable density Navier-Stokes solver for
incompressible flow TERMOFLUIDS. Physical
properties are assumed to vary smoothly in a
narrow band around the interface to avoid numerical
instabilities. Pressure velocity coupling is solved using
a two step projection method where in the first step the
convection, diffusion and source terms are computed
explicitily using the Adams-Bashforth time integration.
In the second step the velocity is corrected by adding
the gradient of the pressure variable. Numerical
solution of pressure Poisson equation is calculated with
an efficient preconditioned conjugate gradient solver.
Mass conservation and convergence properties of the
model are investigated for cases with large density
and viscosity ratios. For the purpose of validation,
numerical results are compared with numerical and
experimental data for standard benchmark problems.DNS of the rising motion of a swarm of bubbles in a confined vertical channel
http://hdl.handle.net/2117/108860
DNS of the rising motion of a swarm of bubbles in a confined vertical channel
Balcázar Arciniega, Néstor; Lehmkuhl Barba, Oriol; Castro González, Jesús; Oliva Llena, Asensio
Thu, 19 Oct 2017 12:39:31 GMThttp://hdl.handle.net/2117/1088602017-10-19T12:39:31ZBalcázar Arciniega, NéstorLehmkuhl Barba, OriolCastro González, JesúsOliva Llena, AsensioAn eulerian-lagrangian modeling of fluidized bed
http://hdl.handle.net/2117/106316
An eulerian-lagrangian modeling of fluidized bed
Zhang, Hao; Yuan-Qiang, Tan; Dong-Min, Yang; Trias Miquel, Francesc Xavier; Sheng, Yong; Oliva Llena, Asensio
The particle motions in a fluidized bed were numerically simulated using a Eulerian-Lagrangian model.
The solid phase was modelled via the Discrete Element Method (DEM) while the hydrodynamic model of the fluid
phase was based on the volume-averaged Navier-Stokes equations. A fluid density-based buoyancy (FDB) model was
adopted to calculate the solid-fluid interaction force. In this paper, the complex ‘four way coupled’ interaction as
proposed by Elghobashi in 1991 was modelled, namely the dominant effect of gas phase on the dispersed particles,
the back influence of the particle phase on the gas phase, and interactions between particles such as collision,
agglomeration and break-up. A stable succession of bubble formation and disappearance was captured. Obtained
pressure drop and interparticle contact number had a good agreement with those reported in previous reference
Mon, 10 Jul 2017 11:03:07 GMThttp://hdl.handle.net/2117/1063162017-07-10T11:03:07ZZhang, HaoYuan-Qiang, TanDong-Min, YangTrias Miquel, Francesc XavierSheng, YongOliva Llena, AsensioThe particle motions in a fluidized bed were numerically simulated using a Eulerian-Lagrangian model.
The solid phase was modelled via the Discrete Element Method (DEM) while the hydrodynamic model of the fluid
phase was based on the volume-averaged Navier-Stokes equations. A fluid density-based buoyancy (FDB) model was
adopted to calculate the solid-fluid interaction force. In this paper, the complex ‘four way coupled’ interaction as
proposed by Elghobashi in 1991 was modelled, namely the dominant effect of gas phase on the dispersed particles,
the back influence of the particle phase on the gas phase, and interactions between particles such as collision,
agglomeration and break-up. A stable succession of bubble formation and disappearance was captured. Obtained
pressure drop and interparticle contact number had a good agreement with those reported in previous referenceAdvanced CFD&HT numerical modeling of solar tower receivers
http://hdl.handle.net/2117/106302
Advanced CFD&HT numerical modeling of solar tower receivers
Colomer Rey, Guillem; Chiva Segura, Jorge; Lehmkuhl Barba, Oriol; Oliva Llena, Asensio
This paper presents an advanced methodology for the detailed modeling of the heat transfer and fluid dynamics phenomena in solar tower receivers. It has been carried out in the framework of a more ambitious enterprise which aims at modeling all the complex heat transfer and fluid dynamics phenomena present in central solar receivers. The global model is composed of 4 sub-models (heat conduction, two-phase flow, thermal radiation and natural convection) which are described.
Mon, 10 Jul 2017 09:29:58 GMThttp://hdl.handle.net/2117/1063022017-07-10T09:29:58ZColomer Rey, GuillemChiva Segura, JorgeLehmkuhl Barba, OriolOliva Llena, AsensioThis paper presents an advanced methodology for the detailed modeling of the heat transfer and fluid dynamics phenomena in solar tower receivers. It has been carried out in the framework of a more ambitious enterprise which aims at modeling all the complex heat transfer and fluid dynamics phenomena present in central solar receivers. The global model is composed of 4 sub-models (heat conduction, two-phase flow, thermal radiation and natural convection) which are described.Numerical study of Taylor bubbles rising in a stagnant liquid using a level-set/moving-mesh method
http://hdl.handle.net/2117/105970
Numerical study of Taylor bubbles rising in a stagnant liquid using a level-set/moving-mesh method
Gutiérrez González, Ernesto; Balcázar Arciniega, Néstor; Bartrons Casademont, Eduard; Rigola Serrano, Joaquim
An Arbitrary Lagrangian-Eulerian formulation has been posed to solve the challenging problem of the three-dimensional Taylor bubble, within a Conservative Level Set (CLS) framework. By employing a domain optimization method (i.e. the moving mesh method), smaller domains can be used to simulate rising bubbles, thus saving computational resources. As the method requires the use of open boundaries, a careful treatment of both inflow and outflow boundary conditions has been carried out. The coupled CLS - moving mesh method has been verified by means of extensive numerical tests. The challenging problem of the full three-dimensional Taylor bubble has then been thoroughly addressed, providing a detailed description of its features. The study also includes a sensitivity analyses with respect to the initial shape of the bubble, the initial volume of the bubble, the flow regime and the inclination of the channel.
Thu, 29 Jun 2017 08:29:59 GMThttp://hdl.handle.net/2117/1059702017-06-29T08:29:59ZGutiérrez González, ErnestoBalcázar Arciniega, NéstorBartrons Casademont, EduardRigola Serrano, JoaquimAn Arbitrary Lagrangian-Eulerian formulation has been posed to solve the challenging problem of the three-dimensional Taylor bubble, within a Conservative Level Set (CLS) framework. By employing a domain optimization method (i.e. the moving mesh method), smaller domains can be used to simulate rising bubbles, thus saving computational resources. As the method requires the use of open boundaries, a careful treatment of both inflow and outflow boundary conditions has been carried out. The coupled CLS - moving mesh method has been verified by means of extensive numerical tests. The challenging problem of the full three-dimensional Taylor bubble has then been thoroughly addressed, providing a detailed description of its features. The study also includes a sensitivity analyses with respect to the initial shape of the bubble, the initial volume of the bubble, the flow regime and the inclination of the channel.Towards a direct numerical simulation of a lifted CH4-air diffusion flame
http://hdl.handle.net/2117/105953
Towards a direct numerical simulation of a lifted CH4-air diffusion flame
Ventosa Molina, Jordi; Lehmkuhl Barba, Oriol; Pérez Segarra, Carlos David; Oliva Llena, Asensio
The near field jet of a self-igniting methane-air diffusion jet flame is studied by means of Direct Numerical Simulation (DNS) and a Flamelet/Progress-Variable (FPV) model to include detailed chemistry. Hence, all flow and transport scales are resolved and chemical reactions are assumed to take place in thin layers. Key aspects in the creation of the flamelet database, prior to the DNS simulation, are considered. Inclusion of differential diffusion effects are discussed by analysing the S-shaped curve and autoignition delay times. Similarly, the influence on these parameters of two detailed mechanism, the GRI2.11 and GRI3.0, is assessed. The definition of the progress-variable used in the FPV is analysed and a new definition is proposed. Results of the near jet, up to 20 jet diameters, are shown for the two detailed mechanism.
Wed, 28 Jun 2017 14:21:19 GMThttp://hdl.handle.net/2117/1059532017-06-28T14:21:19ZVentosa Molina, JordiLehmkuhl Barba, OriolPérez Segarra, Carlos DavidOliva Llena, AsensioThe near field jet of a self-igniting methane-air diffusion jet flame is studied by means of Direct Numerical Simulation (DNS) and a Flamelet/Progress-Variable (FPV) model to include detailed chemistry. Hence, all flow and transport scales are resolved and chemical reactions are assumed to take place in thin layers. Key aspects in the creation of the flamelet database, prior to the DNS simulation, are considered. Inclusion of differential diffusion effects are discussed by analysing the S-shaped curve and autoignition delay times. Similarly, the influence on these parameters of two detailed mechanism, the GRI2.11 and GRI3.0, is assessed. The definition of the progress-variable used in the FPV is analysed and a new definition is proposed. Results of the near jet, up to 20 jet diameters, are shown for the two detailed mechanism.