[Blood flow in the venous system]

Return circulation is studied by describing observed flow solutions: --The direction of the flow is orthograde from the periphery to the right heart, but there ar some inversions. --This permanent flow allows numerous transitory interruptions. --This is a modulated flow, becoming oscillatory in the central veins, and therefore "non-stationary". --Its condition is not exactly laminar. Finally, the venous circulation could be called a "slow-speed system".