Fabián A. Bombardelli, Ph.D.
Professor

Numerical Results Associated with Two-Phase Flows


All videos have been uploaded to YouTube under fabianbombardelli Please go to YouTube if you have difficulties with these links

Stepped spillway: Coherent structures obtained by the Q-criterion. Detached Eddy Simulation. (See video.)

Stepped spillway: Coherent structures in the tranverse direction. Detached Eddy Simulation. (See video.)

Stepped spillway: Coherent structures obtained by the Q-criterion. View from the top. Detached Eddy Simulation. (See video.)

Stepped spillway: Velocity vectors within the cavities; colors indicate vorticity. View at the central vertical plane. Detached Eddy Simulation. (See video.)

Flow past a gate: Velocity vector in air and water at the central vertical plane. (See video.)

Flow past a gate: Coherent structures obtained with the Q-criterion. (See video.)

Flow past a gate: Velocity vectors at the central vertical plane. (See video.)

Flow in a submerged hydraulic jump: Velocity magnitude at the central vertical plane. Approximation to a LES. (See video.)

Flow in a submerged hydraulic jump: Velocity magnitude at the central vertical plane. Detail. Approximation to a LES. (See video.)

Flow in the San Francisco Bay. (See video.)

Flow in the San Francisco Bay. Vertical distribution of velocity vectors at San Francisco. (See video.)

3-D Particle Tracking Code
A three-dimensional (3-D) particle tracking model was developed in FORTRAN, which includes the description of both the particle translational and rotational velocity at every moment. An assessment of existing sub-models for bed roughness representation is introduced in this chapter together with a new sub-model. The validation of the best sub-model is accomplished by comparing its performance with experimental data. The computational code also considers the motion of multiple particles and an algorithm to treat the inter-particle collisions.

Multiple particle simulations under a non turbulent velocity were performed, using the inter-particle collision algorithm  presented in Yamamoto et al. (2001). A video featuring an example of two particles colliding using this methodology is presented here.

2D View of a bed collision and an interparticle collision event. (See video.)

3D View of a bed collision and an interparticle collision event. (See video.)

HR3D  Velocity Field Simulations
The proposed 3-D model coupled with a highly resolved 3-D (HR3D) turbulent velocity field. After its validation, the effect of the turbulence on the particle motion is studied in detail. The interaction between particles, the effect of particle size, volumetric concentration of particles and flow conditions on particle turbulent parameters are discussed in this chapter. A new filter to separate the fluctuating component of the particle velocity from the "mean" value is introduced. .

The particle tracking code was later coupled with a highly-resolved, 3-D, turbulent flow field, to study the effect of the flow turbulence on the particle motion. The one-way coupling model was validated with experimental observations, for the first time in bed load transport. Videos featuring multiple particles under a turbulent velocity field are presented:

Multiple particle simulation. Particle diameter: 0.7 mm, shear velocity: 0.028 m/s. (See video.)

Multiple particle simulation. Particle diameter: 1.0 mm, shear velocity: 0.037 m/s. (See video.)

When considering multiple particles, it is possible to calculate the bed load rate and compare the results with widely used expressions of bed load transport (Julien, 1998). The volumetric sediment transport rate q  is calculated directly by counting the number of particles that moves through a specific location of the simulated channel, in a given period, and multiplying this result by the particle volume. Good agreement between both simulation model and analytical expressions is found.

Department of Civil & Environmental Engineering - University of California, Davis
2001 Ghausi Hall, One Shields Ave., Davis, CA 95616