Flow Rates in Gas-Liquid Simulation

In a gas-liquid simulation, why is the outlet gas flow rate very small compared to the liquid flow rate even though its volume fraction is considerable?

Typically, liquid density to gas density ratios are very high. For example, the density ratio of water to air is ~ 1000 at standard conditions. If volume flow rates of gas and liquid are identical (which implies a gas volume fraction of 0.5), the gas mass flow rate would be as low as 1/1000 times of the liquid mass flow rate, making gas mass flow rate seem very small even though its volume fraction is a considerable number.

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