Which factors determine whether a fluid flow is laminar or turbulent?
Laminar flow occurs at lower velocities, below a threshold at which the flow becomes turbulent. The velocity is determined by a dimensionless parameter characterizing the flow called the Reynolds number, which also depends on the viscosity and density of the fluid and dimensions of the channel.
What do you understand by turbulent flow?
Turbulent flow, type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, or mixing, in contrast to laminar flow, in which the fluid moves in smooth paths or layers. In turbulent flow the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction.
What is K in Nusselt number?
In the case of the Biot number, k is the thermal conductivity of the solid. In the case of the Nusselt number, k is the thermal conductivity of the fluid flowing around the body.
What is the correct formula for Nusselt number?
the Nusselt number, which is NuDh = 890. the hydraulic diameter of the fuel channel is: Dh = 13,85 mm. the thermal conductivity of reactor coolant (300°C) is: kH2O = 0.545 W/m.K. the bulk temperature of reactor coolant at this axial coordinate is: Tbulk = 296°C.
What is average Nusselt number?
A Nusselt number of value one represents heat transfer by pure conduction. A value between one and 10 is characteristic of slug flow or laminar flow. A larger Nusselt number corresponds to more active convection, with turbulent flow typically in the 100–1000 range.
What is the correct formula for Biot number?
Biot number formula h [W/(m² * K)] is the heat transfer coefficient at the material’s surface, k [W/(m * K)] is the thermal conductivity of the material. Bi is the resulting Biot number.
What is Fourier Biot number?
Fourier number is a measure of heat conducted through a body relative to heat stored. The Biot number is the ratio of the internal resistance of a body to heat conduction to its external resistance to heat convection.
What does a low Biot number mean?
Because the Biot number is the ratio between the external resistance of a body to convection energy exchange and internal resistance to transmitting energy by conduction, a small Biot number implies low resistance to transmission by conduction, and therefore very low temperature gradients within the body; thus leading …
When would you use a Biot number?
Biot and Fourier Number simultaneously are applied when the transient heat transfer of an immersed solid body is going to be investigated. It means you should to find out the significance of solid body and environment over heat propagation during the time.
What does Biot mean?
noun. : a statement in electromagnetism: the magnetic intensity at any point due to a steady current in an infinitely long straight wire is directly proportional to the current and inversely proportional to the distance from point to wire — compare ampere’s law.