Density Stoke's Law for Particles having the Density Lower than the Surrounding Medium

It has been observed from our experiments that Stoke's Law can be used only when the particle density is greater than the surrounding medium. When a microbubble is horizontally steered in a liquid, then the Stoke's Law can't be used to calculate the velocity or drag force. The reason underlying is that the density of the microbubble is lower than the density of the liquid. To overcome the problem, a modified Stoke's Law called ``Density Stoke's Law (DSL)'' is proposed. DSL works not only for the particles having the density lower than the surrounding medium, but also for the particles having the density greater than the surrounding medium. Therefore DSL can be considered as a general Stoke's Law.