Gas slippage effect on microscale porous flow using the lattice Boltzmann method

Area of Science:

• Fluid dynamics
• Porous media physics
• Computational physics

Background:

• Gaseous flow in microscale porous media exhibits complex behavior influenced by rarefaction.
• Understanding gas slippage and its impact on permeability is crucial for accurate modeling.
• Existing models may not fully capture the effects of high Knudsen numbers.

Purpose of the Study:

• To develop and apply a lattice Boltzmann method for simulating gaseous slip flow at the pore scale.
• To investigate the influence of Knudsen numbers and pressure ratios on flow characteristics.
• To present a refined model for predicting pressure drop in microscale porous media.

Main Methods:

• Development of a lattice Boltzmann method for pore-scale simulations.
• Analysis of flow through diverse microscale porous geometries.
• Study of varying Knudsen numbers and inlet to outlet pressure ratios.
• Validation against the Klinkenberg equation and extension for higher Knudsen numbers.

Main Results:

• Gas permeability is enhanced by gas slippage, exceeding absolute permeability.
• The impact of rarefaction on gas permeability is more pronounced in low-porosity media.
• The Klinkenberg equation is validated, but the Kn2 term is essential for high Knudsen numbers.
• A new model for pressure drop prediction incorporating rarefaction and compressibility is proposed.

Conclusions:

• Lattice Boltzmann method effectively captures gaseous slip flow phenomena at the pore scale.
• Gas slippage significantly alters permeability, particularly in low-porosity porous media.
• Accurate modeling of microscale porous media flow requires considering higher-order rarefaction effects and compressibility.