Introduction to the Ansys Fluent Hybrid VOF to DPM Model

Ansys Fluent Hybrid VOF | Webinar Description:

This webinar discusses Ansys Fluent’s Hybrid VOF to DPM multiphase model.

Ansys Fluent Hybrid Volume of Fluids (VOF)

This robust adaptation allows users to model primary atomization and subsequent breakup, evaporation and chemical reactions in the same setting.

Volume of fluid (VOF) is a desired way for simulating surface and interface location.  Essentially, a marker method from the family of surface tracking systems. Therefore, it is an option if we want to imitate the position of the surface or contact. Regardless of the interface tracking technique, the Navier-Stokes equations and the species concentration conservation equation must be solved.  Specifically, using a suitable turbulence model in order to simulate mixing. The vast majority of CFD algorithms that employ the VOF method are capable of solving such engineering inquiries.  That is, both the species concentration equation and the entire set of Navier-Stokes equations.

Deploying Multifluid VOF Modeling to Simulate Air–Water Churn Flow

Different industrial processes can exhibit gas-liquid multiphase flow.  Moreover, computational fluid dynamics (CFD) can be used as a technique to examine these flows. Although computationally intensive, multiphase CFD simulations can provide a wealth of information. But the more important question is: Can a complex flow pattern like churn flow be solved?  More specifically, accurately using the CFD multiphase flow models that are now available?  If so, to what degree are the outcomes accurate?

High flow rate air-water multiphase flow in a 76.2 mm-diameter pipe upstream of an elbow was simulated.  That is, using the Eulerian-Eulerian Multifluid VOF model provided by ANSYS FLUENT 15 (Ansys 15.0 User’s Guide, ANSYS Inc.) to clarify these concerns.  Specifically, air-water multiphase flow in a vertical-horizontal pattern.  The simulations used two superficial liquid velocities of 0.3 and 0.79 m/s and two superficial gas velocities that ranged from 10.3 to 33.9 m/s.

Simulate Air-Water Churn Flow

Data such as phase distributions, mean void fractions, and average void fraction time series were collected from the CFD simulations. These are one to two subchannels covered by large, violently moving bubbles.  As such, then contrasting results with earlier collected experimental Wire Mesh Sensor (WMS) data.  Curiously, evaluation of the model showed that it was effective in capturing various liquid structures present,  Specifically, in the flow and providing void fraction statistics that agreed with experiment results.  Such precision is required to accurately simulate air-water churn flow.

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