An Animal Waste Supply CFD simulation is a computer model of a bioreactor used for Anaerobic Digestion CFD. This process is a core part of Waste-to-Energy Simulation technology. It involves using animal waste, or slurry, to produce biogas, which is a form of renewable energy. An Animal Waste Supply Fluent analysis helps engineers design better systems by showing how the liquid waste and the gas it produces separate. This is a Multiphase Flow in Bioreactors problem. By understanding this process, we can build more efficient systems for Biogas Production Simulation, which is important for sustainable farming and protecting the environment.

Figure 1:  A schematic of the two-chamber animal waste supply system used for the Anaerobic Digestion CFD analysis.

Simulation Process: Fluent VOF Setup, Modeling Transient Multiphase Biogas Flow

To perform this Slurry Flow CFD study, we first created the 3D geometry, which includes two chambers connected by pipes. Then, using ANSYS Meshing, we generated a high-quality structured grid with 206,018 hexagonal cells, which is ideal for this type of simulation. In ANSYS Fluent, we used the transient solver because the process of filling the chamber and collecting gas happens over time. Most importantly, we activated the Volume of Fluid (VOF) multiphase model. The VOF model is the correct choice here because it is excellent at tracking the clear interface, or surface, between two fluids that do not mix, like the liquid animal waste and the gaseous biogas.

Figure 2: The structured hexahedral grid containing 206,018 cells, created for the VOF Model Fluent simulation of the bioreactor.

Post-processing: CFD Analysis, Biogas Separation Efficiency and Phase Distribution

The volume fraction contour acts as a clear diagnostic map of the system’s state at 2334.68 seconds into the process. From an engineering standpoint, this visual provides direct proof that the system is working as designed. The left chamber is almost entirely filled with the liquid waste phase, shown in dark blue. This indicates it is the primary storage or reaction chamber where anaerobic digestion occurs. In contrast, the right chamber is almost entirely filled with the gas phase (biogas), shown in bright red, with an air volume fraction of 0.957. This shows it is successfully acting as a gas collection chamber.

Figure 3: A volume fraction contour from the Transient CFD Simulation at 2334.68 seconds, showing the clear separation of biogas (red) from the animal waste slurry (blue).

The key engineering insight from this analysis is the sharpness of the separation. The contour shows a very clean interface between the liquid waste and the collected biogas, with very little mixing. This indicates that the transfer process is efficient and that the collected gas is of high purity, with minimal liquid carryover. The simulation confirms that the geometry of the pipes and chambers allows the low-density biogas, produced from the slurry, to naturally rise and flow into the collection chamber. The most important achievement of this simulation is its ability to validate the design concept, demonstrating that the two-chamber system effectively separates and collects biogas from the animal waste slurry through passive, buoyancy-driven flow.