Reynolds’ Experiment

Aim: To conduct Reynold’s experiment for assessment of various regimes of the flow


The flow of real liquids can fundamentally happen under two altogether different regimes in particular laminar and turbulent flow. The laminar flow is described by liquid particles moving as lamina sliding over each other, with the end goal that at any moment velocity specifically lamina is the same. The lamina close to the flow limit move at a slower rate when contrasted with those close to the focal point of the flow section. This kind of flow happens in gooey liquids , liquids moving at moderate speed and liquids flowing through tight sections.

The turbulent flow is portrayed by steady disturbance and intermixing of liquid particles with the end goal that their speed changes from indicates point and even at a similar indicate from time. This sort of flow happens in low density.

Liquids, flow through wide entry and in high velocity flows.

Reynolds led a trial for the observation and assurance of these administrations of flow. By presenting a fine fiber of color into the flow of water through the glass tube ,at its passageway he concentrated the distinctive sorts of flow. At low speeds the color fiber showed up as straight line through the length of the tube and parallel to its hub, portraying laminar flow. As the speed is expanded the color fiber gets to be distinctly wavy all through showing move flow. On further expanding the speed the fiber separates and diffuses totally in the water in the glass tube showing the turbulent flow.

In the wake of his experiment with different pipes with varying diameters and with liquid at various temperatures, Reynolds inferred that the different parameters on which the regimes of flow depend can be gathered together in a solitary non dimensional parameter called Reynolds number. Reynolds number is characterized as, the proportion of inertia per unit volume and is given by:

Re=vD?/ µ =VD/v


Re-Reynolds number

V -velocity of flow

D-characteristic length=diameter in case of pipe flow

?-mass density of fluid

µ-dynamic viscosity of fluid

v -kinematic viscosity of fluid

Reynolds noticed that in situations of flow via pipe for values of Re smaller than 2000 the flow is laminar while offer Re greater 40000 it is turbulent and for 2000<Re<4000 it is known as transition flow.


A stop watch

A graduated cylinder

Reynolds apparatus which includes of water tank having a glass tube leading out of it.


  1. Completely fill up the water tank with water and permit it to stand for some time period so that the water will come to state of rest.
  2. Mark the temperature of water.
  3. Partly unlock the outlet valve of the glass tube and permit the flow to happen at a very low rate.
  4. Permit the flow of water to even out then open the valves at the inlet of the dye injector and permit the dye to shift through the tube. Monitor the temperament of the filament.
  5. Calculate the release by gathering water in the graduated cylinder for a definite period of time.
  6. Reiterate the steps 3 and 5 for different discharges
  7. Once again mark the temperature of water


Mean temperature of water – t –

Kinematic viscosity of water-v-

Diameter of glass tube-D-

reynold's number experiment

Conduct the subsequent calculations for all sets of readings

Discharge -Q-Axh /t

Velocity of flow – V-4Q /(?D2)

Reynolds number -Re-VD/v