Bridge Pillars External Two-Phase Flow CFD Simulation

This training episode focuses on simulating the interaction between water flow and bridge pillars using ANSYS Fluent’s Volume of Fluid (VOF) model. The VOF method is particularly well-suited for this scenario as it excels at capturing the interface between two immiscible fluids, in this case, water and air.

Key aspects covered in this simulation:

VOF model setup: Configuring the VOF model to simulate the free surface flow around the bridge pillars. This includes setting up phase interactions, defining primary and secondary phases, and specifying surface tension effects if applicable.

Boundary conditions: Defining inlet, outlet, and wall conditions to represent realistic river flow. This may include velocity inlet for water, pressure outlet, and no-slip conditions for the pillars and riverbed.

Turbulence modeling: Selecting and setting up a suitable turbulence model for external flows, such as k-epsilon or k-omega SST, and adjusting turbulence parameters for multiphase flow.

Solution methods: Choosing appropriate discretization schemes and algorithms for pressure-velocity coupling in the context of VOF simulations.

Transient simulation setup: Configuring time-step sizes, number of time steps, and convergence criteria for the time-dependent simulation to capture the dynamic behavior of water around the pillars.

Initialization and calculation: Properly initializing the simulation and running it to achieve a converged solution.

Post-processing: Analyzing results such as water surface elevation, velocity profiles, and pressure distribution on the pillars. This includes creating meaningful visualizations of the free surface and flow patterns.

Vortex shedding analysis: Observing and quantifying vortex shedding phenomena behind the pillars using appropriate post-processing techniques.

This simulation provides valuable insights into hydraulic loads on bridge structures, scour potential around pillars, and overall flow patterns in rivers with obstructions. Participants will gain hands-on experience in applying the VOF model to a complex external flow problem, enhancing their skills in multiphase CFD simulations using ANSYS Fluent, with a focus on model setup, solution strategies, and result interpretation.