Effect of a dissolved gas on the flow rate of water through a porous medium

When a water-containing gas which has been dissolved under high pressure flows through a porous medium containing pores of colloidal dimensions, there is an increase in the rate of flow. Two porous media were studied; a membrane made of fine particles of silver and a nuclepore membrane with straight cylindrical pores. The effect of the dissolved gas on the flow rate of the water depended on the pore diameter (the hydraulic radius), the concentration of the dissolved gas, and the type of membrane, but was independent of the nature of the dissolved gas. An empirical equation was derived for the flow rate of water containing a dissolved gas through a porous medium. The formation of bubbles as the pressure decreased and the adhesion of these bubbles to the pore surfaces suggests that the observed increase in the flow rate is due to slippage on the pore surfaces as a result of the presence of the bubbles.