What is grashof condition?
The Grashof condition for a four-bar linkage states: If the sum of the shortest and longest link of a planar quadrilateral linkage is less than or equal to the sum of the remaining two links, then the shortest link can rotate fully with respect to a neighboring link.
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 physical significance of the Grashof number differentiate between the Grashof number and the Reynolds number?
It represents how dominant is the buoyancy force which is responsible for the convection comparing to the viscous forces. Grashof number is very similar to the reynold’s number . Only difference is that Reynolds Number is used for forced convection cases where Grashod number is used for natural convection phenomenon.
At what temperature should the properties used in the Grashof number be evaluated?
The fluid properties used to calculate the Grashof number should be evaluated at the film temperature, the arithmetic mean between the bulk and wall temperatures. This will require determining an additional set of property values.
How does the Grashof number differ from the Reynolds number?
How does the Grashof number differ from the Reynolds number? In natural convection, Grashof number dictates whether the flow is laminar or turbulent. If the number is greater than then the flow is turbulent.
What does a high value of Prandtl number indicate?
Physical Interpretation. Small values of the Prandtl number, Pr << 1, means the thermal diffusivity dominates. Whereas with large values, Pr >> 1, the momentum diffusivity dominates the behavior. When Pr is small, it means that the heat diffuses quickly compared to the velocity (momentum).
What is the value of Prandtl number for highly viscous oils?
Prandtl number is a characteristic of the fluid only. For air at room temperature Pr is 0.71 and most common gases have similar values. The Prandtl number of water at 17°C is 7.56. Liquids in general have high Prandtl numbers, with values as high as 105 for some oils.