Multiphase Flows

Multiphase Flows Fluid Simulation Software

Chances are that your fluids simulation includes multiphase flows like boiling, cavitation, dispersed multiphase flows, immiscible flows and flows with particulates. ANSYS CFD provides the widest range of sophisticated turbulence and physical models to accurately simulate the toughest challenges so you can confidently predict your product’s performance.

Many fluids simulations include multiphase flows. Whether you are designing a super-fast transport and need to counter ice build-up, developing a blood enzyme test, delivering and melting rare metallic powder compounds for additive manufacturing, or designing a filtration system to provide clean drinking water in a remote location, you are solving multiphase problems.

As we push the boundaries to improve our products and processes, we need to gain a better understanding of how liquids, solids and gases interact. Each of these varied multiphase challenges requires a different modelling approach. Our customers have been using ANSYS CFD for over 40 years to achieve the widest range of accurate multiphase models and confidently predict their product’s performance. To truly understand your product, you must get your multiphase simulations right.

Fluent AIAD accurately simulates complex multiphase regime transitions like the air-water flow in this 180 degree pipe bend.
Read the Multiphase Flows application brief

New: Fluent generalized two-phase (GENTOP) model for multiphase regime transitions

Transitions between continuous and dispersed flow structures are usually difficult to model. These flows can be encountered in a large number of applications, including boiling, condensation, container filling, sloshing in fuel tanks, centrifuges and mixing tanks.

The GENTOP model can be used for simulating these types of applications where different interfacial structures occur simultaneously. The model works as an extension of the inhomogeneous discrete population balance method, which allows you to define different secondary phases with their own velocity fields, permitting an almost seamless transition from dispersed to continuous structures. Since GENTOP is built on the Euler-Euler approach, it allows for the use of coarser meshes in comparison to VOF or Multi-Fluid VOF, without sacrificing solution robustness. An advanced single, tabbed panel with best practices embedded in each selection streamlines the GENTOP setup. This makes the model useful and user-friendly for both novice and expert users alike.

Why Shallow Containers Slosh

To avoid severe load instabilities, engineers often face strict design requirements to control sloshing of liquid in moving containers, such as tanker trucks or rockets. In these applications, designers usually insert interior baffle plates or similar structures to impede the flow of liquid. Other application involving sloshing liquids include harbor design or the study of long-wavelength tsunami waves. In all these cases, simulation plays a key role in predicting sloshing and evaluating ways to solve the problem.

Alex helps us demonstrate sloshing. Analysis indicates that the first sloshing mode is 1.6 Hz,
the frequency at which the bowl is prone to resonance and spills its contents.

An example of sloshing is the carrying of a dog bowl full of water, in which the liquid has the tendency to slop from side to side and often spill. A multiphase simulation of this free surface flow reveals that this behavior occurs because the first sloshing mode of the bowl is roughly at 2 Hz — the typical human step frequency that excites this undesired resonance. Repeating the analysis for a glass of water reveals a first sloshing mode of 4 Hz, which shows why water glasses are much less prone to spilling than bowls. In these simulations, the structural walls have been assumed to be rigid. Engineers also can study sloshing in elastic vessels such as reactor containment structures using the fluid–structure interaction (link to FSI Application page) capabilities in ANSYS software.
By Marold Moosrainer, CADFEM

See ANSYS Multiphase Capabilities