Question:
Natural convection is associated with which of the following dimensionless numbers?
Natural convection is associated with which of the following dimensionless numbers?
Show Hint
Remember the primary dimensionless pairings:
- Forced Convection \(\rightarrow\) Reynolds number (\(\text{Re}\))
- Natural Convection \(\rightarrow\) Grashof number (\(\text{Gr}\))
This distinction is a fundamental concept in convective heat transfer.
- Forced Convection \(\rightarrow\) Reynolds number (\(\text{Re}\))
- Natural Convection \(\rightarrow\) Grashof number (\(\text{Gr}\))
This distinction is a fundamental concept in convective heat transfer.
Updated On: Jul 23, 2026
- Prandtl number
- Reynolds number
- Grashof number
- Nusselt number
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Convective heat transfer occurs through two primary mechanisms: natural (free) convection and forced convection.
- Natural convection is driven entirely by buoyancy forces within a fluid. These forces arise from density differences caused by temperature gradients.
- Dimensionless numbers are used to model and scale these heat transfer processes.
Step 2: Detailed Explanation:
Let us analyze the physical significance of each dimensionless number listed:
- Prandtl number (\(\text{Pr}\)): Represents the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity. It is a fluid property that is independent of the flow type.
- Reynolds number (\(\text{Re}\)): Represents the ratio of inertial forces to viscous forces in a fluid flow. It is the primary parameter used to characterize forced convection.
- Nusselt number (\(\text{Nu}\)): Represents the ratio of convective heat transfer to conductive heat transfer across a boundary. It is used in both natural and forced convection to determine heat transfer rates.
- Grashof number (\(\text{Gr}\)): Represents the ratio of buoyancy forces to viscous forces acting on a fluid. Since buoyancy is the driving force behind natural convection, the Grashof number serves as the primary parameter to characterize and govern free convective heat transfer.
Therefore, natural convection is specifically associated with the Grashof number.
Step 3: Final Answer:
Natural convection is associated with the Grashof number. Hence, the correct option is (C).
Convective heat transfer occurs through two primary mechanisms: natural (free) convection and forced convection.
- Natural convection is driven entirely by buoyancy forces within a fluid. These forces arise from density differences caused by temperature gradients.
- Dimensionless numbers are used to model and scale these heat transfer processes.
Step 2: Detailed Explanation:
Let us analyze the physical significance of each dimensionless number listed:
- Prandtl number (\(\text{Pr}\)): Represents the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity. It is a fluid property that is independent of the flow type.
- Reynolds number (\(\text{Re}\)): Represents the ratio of inertial forces to viscous forces in a fluid flow. It is the primary parameter used to characterize forced convection.
- Nusselt number (\(\text{Nu}\)): Represents the ratio of convective heat transfer to conductive heat transfer across a boundary. It is used in both natural and forced convection to determine heat transfer rates.
- Grashof number (\(\text{Gr}\)): Represents the ratio of buoyancy forces to viscous forces acting on a fluid. Since buoyancy is the driving force behind natural convection, the Grashof number serves as the primary parameter to characterize and govern free convective heat transfer.
Therefore, natural convection is specifically associated with the Grashof number.
Step 3: Final Answer:
Natural convection is associated with the Grashof number. Hence, the correct option is (C).
Was this answer helpful?
0
0
Top ICAR AIEEA Dairy Technology Questions
- As per legal standards (FSSR, 2011), the acidity (%LA) of chakka should not be more than:
- Which of the following food additive is permitted as preservative in paneer?
- Given below are four statements:
Statement (I) : Homogenisation breaks down fat globules in milk into smaller entities.
Statement (II) : Homogenisation breaks down fat globules and casein micelles in milk into smaller entities.
Statement (III) : Homogenisation slightly increases viscosity of milk.
Statement (IV) : Homogenisation improves the appearance of milk.
In light of the above statements, choose the most appropriate answer from the options given below. - With regard to temperature of operation, place the following unit operations in sequence in an increasing order of temperature:
(i) Sterilisation
(ii) Thermisation
(iii) Homogenisation
(iv) Bactofugation and
(v) HTST pasteurization.
Choose the correct answer from the options given below : - “Narampak” and “karapak” refer to varieties of sandesh with reference to which of the following parameters ?
View More Questions
Top ICAR AIEEA Heat Transfer and Unit Operations Questions
- With regard to temperature of operation, place the following unit operations in sequence in an increasing order of temperature:
(i) Sterilisation
(ii) Thermisation
(iii) Homogenisation
(iv) Bactofugation and
(v) HTST pasteurization.
Choose the correct answer from the options given below : - Match List-I with List-II
\begin{tabular{ll} List-I (Name of Process) & List-II (Temperature/time)
(A) Pasteurization & (I) \(60\ ^\circ\text{C}\) no hold
(B) Sterilisation & (II) \(55-60\ ^\circ\text{C}\) no hold
(C) Homogenisation & (III) \(72\ ^\circ\text{C}\) 15 sec
(D) Bactofugation & (IV) \(118\ ^\circ\text{C}\) 15min
Choose the correct answer from the options given below : - In falling film milk evaporator, the temperature difference between milk and steam should be approximately around :
- Indirect UHT treatment can be done using which of the following methods ?
- Which of the following value is related to sterilization process ?
View More Questions
Top ICAR AIEEA Questions
- Which of the following statements is false?
- Which of the following is an example of an inventory?
- According to Adam Smith, productivity gains could be brought about through .
- The supply curve for an artificially scarce good is .
- Which of the following would not be considered an opportunity cost of paid employment?
View More Questions