Separation efficiency of a hydrodynamic separator using a 3D computational fluid dynamics multiscale approach.

Area of Science:

• Fluid Dynamics
• Particle Separation Technology

Background:

• Hydrodynamic separators are crucial for solid-liquid separation.
• Accurate prediction of separation efficiency is vital for optimizing device design and performance.
• Numerical simulation challenges include modeling complex geometries and local phenomena.

Purpose of the Study:

• To investigate the application of computational fluid dynamics (CFD) for predicting the solid separation efficiency of hydrodynamic separators.
• To utilize a multiscale CFD approach combining global and local models for comprehensive analysis.
• To evaluate the influence of particle characteristics and screen design on separation performance.

Main Methods:

• A multiscale computational fluid dynamics (CFD) approach was employed, integrating a global device model and a local screen model.
• The Eulerian-Lagrangian method was used to simulate particle trajectories within both models.
• Two screen types, perforated plates and expanded metal, were compared to assess turbulent effects.

Main Results:

• The global model demonstrated that higher particle density enhances sedimentation and separation efficiency.
• Particles with densities close to the fluid (1,040 kg/m³) are significantly influenced by hydrodynamics and can be effectively trapped.
• The local model revealed distinct particle trajectories near the screen, with screen geometry inducing turbulent effects.

Conclusions:

• CFD, particularly the multiscale approach, is a viable tool for predicting hydrodynamic separator performance.
• Particle density and hydrodynamic forces are key factors governing separation efficiency.
• Screen design critically impacts local flow dynamics and turbulence, influencing overall separation outcomes.