Devices for generating discrete flow of liquids in response to a driving force, for example centrifugal microfluidic devices for generating discrete flow in response to a constant driving force. The device includes a supply structure for supplying liquid at an inflow rate to a discretization structure in response to a driving force. The discretization structure is shaped to define an outlet and a level to which the discretization structure fills with liquid flowing from the supply structure before dispensing the liquid at an outflow rate through the outlet in response to the driving force. The device is arranged such that the outflow rate from the discretization structure is greater than the inflow rate into the discretization structure, thereby periodically emptying the discretization structure to create a discretized flow from the outlet. The devices find applications in liquid mixing, for example for diluting samples, such as blood plasma samples.