Subgrid-scale modeling suggested by a two-scale DIA

Yoshizawa, Akinori

doi:10.1016/0167-6105(93)90161-g

Cited by 2 publications

(3 citation statements)

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“…where ν f is the kinematic viscosity of the pure fluid, ν t is the turbulent viscosity, C s Smagorinsky constant, and 𝐴𝐴 𝐴𝐴𝐴𝑓𝑓 the fluid local shear rate. C s is shown to be dependent on the discretization and geometry (Hou et al, 1994;Yoshizawa, 1993). We calibrate C s = 0.27 in the flume geometry (see Appendix A for details and for validation of the pure fluid simulations) with grid size dx = 0.5 mm.…”

Section: Method: Dem-lbmmentioning

confidence: 99%

“…We use the Smagorinsky turbulent closure (Smagorinsky, 1963):

\nu ={\nu }_{f}+{\nu }_{t},\quad {\nu }_{t}={\left({C}_{s}\cdot dx\right)}^{2}{\dot{\gamma }}_{f},

where ν f is the kinematic viscosity of the pure fluid, ν t is the turbulent viscosity, C s Smagorinsky constant, and

{\dot{\gamma }}_{f}

the fluid local shear rate. C s is shown to be dependent on the discretization and geometry (Hou et al., 1994; Yoshizawa, 1993). We calibrate C s = 0.27 in the flume geometry (see Appendix A for details and for validation of the pure fluid simulations) with grid size dx = 0.5 mm.…”

Section: Discrete Simulationsmentioning

confidence: 99%

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Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

et al. 2022

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Bedload sediment transport is ubiquitous in shaping natural and engineered landscapes, but the variability in the relation between sediment flux and driving factors is not well understood. At a given Shields number, the observed dimensionless transport rate can vary over a range in controlled systems and up to several orders of magnitude in natural streams. Here, we (a) experimentally validate a resolved fluid‐grain numerical scheme (Lattice Boltzmann Method‐Discrete Element Method or DEM‐LBM), and use it to (b) explore the parameter space controlling sediment transport in simple systems. Wide wall‐free simulations show the dimensionless transport rate is not influenced by the slope, fluid depth, mean particle size, particle surface friction, or grain‐grain damping for gentle slopes (0.01–0.03) at a medium to high fixed Shields number. (c) Examination of small‐scale fluid‐grain interactions shows fluid torque is non‐negligible for the entrainment and sediment transport near the threshold. And (d) the simulations guide the formulation of continuum models for the transport process. We present an upscaled two‐phase continuum model for grains in a turbulent fluid and validate it against bedload transport DEM‐LBM simulations. To model the creeping granular flow under the bed surface, we use an extension of the Nonlocal Granular Fluidity model, which was previously shown to account for flow cooperativity from grain‐size‐effects in dry media. The model accurately predicts the exponentially decaying velocity profile deeper into the bed.

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Section: Method: Dem-lbmmentioning

confidence: 99%

“…We use the Smagorinsky turbulent closure (Smagorinsky, 1963):

\nu ={\nu }_{f}+{\nu }_{t},\quad {\nu }_{t}={\left({C}_{s}\cdot dx\right)}^{2}{\dot{\gamma }}_{f},

where ν f is the kinematic viscosity of the pure fluid, ν t is the turbulent viscosity, C s Smagorinsky constant, and

{\dot{\gamma }}_{f}

Section: Discrete Simulationsmentioning

confidence: 99%

Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

et al. 2022

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“…represents the resolved rate-of-strain tensor, ∆ is the grid size and C S as the Smagorinsky constant, which usually has the value 0.1 to 0.2. For the present study the used value for this constant is C S = 0.1667, since it is within the range for representing mixing layer flows [36].…”

Section: The Smagorinsky Modelmentioning

confidence: 99%

Validation of Actuator Line and Vortex Models Using Normal Forces Measurements of a Straight-Bladed Vertical Axis Wind Turbine

Mendoza

Goude

2020

Energies

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Vertical Axis Wind Turbines (VAWTs) are characterized by complex and unsteady flow patterns resulting in considerable challenges for both numerical simulations and measurements describing the phenomena involved. In this study, a 3D Actuator Line Model (ALM) is compared to a 2D and a 3D Vortex Model, and they are validated using the normal forces measurements on a blade of an operating 12 kW VAWT, which is located in an open site in the north of Uppsala, Sweden. First, the coefficient power ( C P ) curve of the device has been simulated and compared against the experimental one. Then, a wide range of operational conditions for different tip speed ratios (TSRs), with λ = 1.84, 2.55, 3.06, 3.44, 4.09 and 4.57 were investigated. The results showed descent agreement with the experimental data for both models in terms of the trend and magnitudes. On one side, a slight improvement for representing the normal forces was achieved by the ALM, while the vortex code performs better in the simulation of the C P curve. Similarities and discrepancies between numerical and experimental results are discussed.

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Subgrid-scale modeling suggested by a two-scale DIA

Cited by 2 publications

References 0 publications

Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

Validation of Actuator Line and Vortex Models Using Normal Forces Measurements of a Straight-Bladed Vertical Axis Wind Turbine

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