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Joan Baiges - One of the best experts on this subject based on the ideXlab platform.

  • Pseudoplastic Fluid Flows for different Prandtl numbers: Steady and time-dependent solutions
    International Journal of Thermal Sciences, 2019
    Co-Authors: A. Aguirre, Ernesto Castillo, Marcela A. Cruchaga, Ramon Codina, Joan Baiges
    Abstract:

    Abstract In this work, a variational multiscale (VMS) finite element formulation is used to approximate numerically the natural convection in square cavity with differentially heated from sidewalls problem for Newtonian and power-law Fluids. The problem is characterized for going through a Hopf bifurcation when reaching high enough Rayleigh numbers, which initiates the transition between steady and time dependent behavior, however, results found in the literature are only for air Prandtl number. The presented VMS formulation is validated using existing results, and is used to study highly convective cases, to determine the flow conditions at which it becomes time dependent, and to establish new benchmark solutions for Non-Newtonian Fluid Flows for different Pr and power-law indexes n. The range of solutions were found in the range 0.6 n 1 and 0.01 P r 1,000 , and the critical Rayleigh number ( Ra c ) where Hopf bifurcations appear were identified for all cases. Obtained results have good agreement with those previously reported in the specific literature, and new data related to the heat transfer capabilities of pseudoplastic Fluids and its oscillatory behavior was identified. This Non-Newtonian influence of the Fluid is later checked in a 3 D model of a simplified heat exchanger, where the capability of pseudoplastic Fluids for energy transport proved to be enhanced when compared to the Newtonian case.

A. Aguirre - One of the best experts on this subject based on the ideXlab platform.

  • Pseudoplastic Fluid Flows for different Prandtl numbers: Steady and time-dependent solutions
    International Journal of Thermal Sciences, 2019
    Co-Authors: A. Aguirre, Ernesto Castillo, Marcela A. Cruchaga, Ramon Codina, Joan Baiges
    Abstract:

    Abstract In this work, a variational multiscale (VMS) finite element formulation is used to approximate numerically the natural convection in square cavity with differentially heated from sidewalls problem for Newtonian and power-law Fluids. The problem is characterized for going through a Hopf bifurcation when reaching high enough Rayleigh numbers, which initiates the transition between steady and time dependent behavior, however, results found in the literature are only for air Prandtl number. The presented VMS formulation is validated using existing results, and is used to study highly convective cases, to determine the flow conditions at which it becomes time dependent, and to establish new benchmark solutions for Non-Newtonian Fluid Flows for different Pr and power-law indexes n. The range of solutions were found in the range 0.6 n 1 and 0.01 P r 1,000 , and the critical Rayleigh number ( Ra c ) where Hopf bifurcations appear were identified for all cases. Obtained results have good agreement with those previously reported in the specific literature, and new data related to the heat transfer capabilities of pseudoplastic Fluids and its oscillatory behavior was identified. This Non-Newtonian influence of the Fluid is later checked in a 3 D model of a simplified heat exchanger, where the capability of pseudoplastic Fluids for energy transport proved to be enhanced when compared to the Newtonian case.

Sauro Succi - One of the best experts on this subject based on the ideXlab platform.

  • Enhanced computational performance of the lattice Boltzmann model for simulating micron- and submicron-size particle Flows and Non-Newtonian Fluid Flows
    Computer Physics Communications, 2017
    Co-Authors: Hakan Başağaoğlu, John R. Harwell, Hoa Nguyen, Sauro Succi
    Abstract:

    Abstract Significant improvements in the computational performance of the lattice-Boltzmann (LB) model, coded in FORTRAN90, were achieved through application of enhancement techniques. Applied techniques include optimization of array memory layouts, data structure simplification, random number generation outside the simulation thread(s), code parallelization via OpenMP, and intra- and inter-timestep task pipelining. Effectiveness of these optimization techniques was measured on three benchmark problems: (i) transient flow of multiple particles in a Newtonian Fluid in a heterogeneous fractured porous domain, (ii) thermal fluctuation of the Fluid at the sub-micron scale and the resultant Brownian motion of a particle, and (iii) Non-Newtonian Fluid flow in a smooth-walled channel. Application of the aforementioned optimization techniques resulted in an average 21 × performance improvement, which could significantly enhance practical uses of the LB models in diverse applications, focusing on the fate and transport of nano-size or micron-size particles in Non-Newtonian Fluids.

K Wakabayashi - One of the best experts on this subject based on the ideXlab platform.

  • friction and heat and mass transfer for turbulent pseudoplastic non newtonian Fluid Flows in rough pipes
    Canadian Journal of Chemical Engineering, 1994
    Co-Authors: Yoshinori Kawase, A V Shenoy, K Wakabayashi
    Abstract:

    Friction factor and heat and mass transfer coefficient correlations are developed for turbulent pseudoplastic (purely viscous or inelastic) Non-Newtonian Fluids flowing through rough pipes. A correlation for friction factor which is applicable in the region of transition from the smooth to the fully-rough regime is proposed. It is obtained by adding the two correlations for the limiting situations, i.e. smooth pipes and fully-rough pipes. The predictions of the proposed correlation are compared with published experimental data and other previous correlations. A model for heat and mass transfer is developed on the basis of the Levich three-zone model. It is found that the proposed model is capable of predicting satisfactorily heat and mass transfer coefficients for Newtonian and pseudoplastic Non-Newtonian Fluid flow in rough pipes.

  • Friction and heat and mass transfer for turbulent pseudoplastic non‐newtonian Fluid Flows in rough pipes
    The Canadian Journal of Chemical Engineering, 1994
    Co-Authors: Yoshinori Kawase, A V Shenoy, K Wakabayashi
    Abstract:

    Friction factor and heat and mass transfer coefficient correlations are developed for turbulent pseudoplastic (purely viscous or inelastic) Non-Newtonian Fluids flowing through rough pipes. A correlation for friction factor which is applicable in the region of transition from the smooth to the fully-rough regime is proposed. It is obtained by adding the two correlations for the limiting situations, i.e. smooth pipes and fully-rough pipes. The predictions of the proposed correlation are compared with published experimental data and other previous correlations. A model for heat and mass transfer is developed on the basis of the Levich three-zone model. It is found that the proposed model is capable of predicting satisfactorily heat and mass transfer coefficients for Newtonian and pseudoplastic Non-Newtonian Fluid flow in rough pipes.

Ramon Codina - One of the best experts on this subject based on the ideXlab platform.

  • Pseudoplastic Fluid Flows for different Prandtl numbers: Steady and time-dependent solutions
    International Journal of Thermal Sciences, 2019
    Co-Authors: A. Aguirre, Ernesto Castillo, Marcela A. Cruchaga, Ramon Codina, Joan Baiges
    Abstract:

    Abstract In this work, a variational multiscale (VMS) finite element formulation is used to approximate numerically the natural convection in square cavity with differentially heated from sidewalls problem for Newtonian and power-law Fluids. The problem is characterized for going through a Hopf bifurcation when reaching high enough Rayleigh numbers, which initiates the transition between steady and time dependent behavior, however, results found in the literature are only for air Prandtl number. The presented VMS formulation is validated using existing results, and is used to study highly convective cases, to determine the flow conditions at which it becomes time dependent, and to establish new benchmark solutions for Non-Newtonian Fluid Flows for different Pr and power-law indexes n. The range of solutions were found in the range 0.6 n 1 and 0.01 P r 1,000 , and the critical Rayleigh number ( Ra c ) where Hopf bifurcations appear were identified for all cases. Obtained results have good agreement with those previously reported in the specific literature, and new data related to the heat transfer capabilities of pseudoplastic Fluids and its oscillatory behavior was identified. This Non-Newtonian influence of the Fluid is later checked in a 3 D model of a simplified heat exchanger, where the capability of pseudoplastic Fluids for energy transport proved to be enhanced when compared to the Newtonian case.