# Which are the dimensionless parameters?

## Which are the dimensionless parameters?

Dimensionless Parameter

• Mass Transfer.
• Heat Exchanger.
• Viscosity.
• Boundary Condition.
• Prandtl Number.
• Reynolds’ Number.

How many dimensionless parameters are there?

The six dimensionless numbers give the relative strengths of the different phenomena of inertia, viscosity, conductive heat transport, and diffusive mass transport.

What are dimensionless parameters important in heat transfer?

The Dimensionless numbers we will describe in this article are the most common numbers used in heat transfer: Reynolds Number. Nusselt Number. Prandtl Number. Grashof Number.

### What are the dimensionless parameters used in forced convection?

1. Reynolds number [Re]. 2. Nusselt number [Nu].

How do you find dimensionless parameters?

Once j is found, the number of dimensionless parameters (or “Pi” groups) expected is k = n – j, where k is the number of Pi groups. This equation relating k to n and j is part of the Buckingham Pi Theorem.

What are the dimensionless parameters used in forced and free convection heat transfer analysis?

Grashof number (Gr) and Prandtl number (Pr) product is Known as the Rayleigh Number(Ra). It is used for free convection.

#### Which are the factors affecting heat transfer by forced convection?

Forced motion of fluid or forced convection occurs under the influence of some external agency such as wind, pump and agitation fan etc. Forced convection depends on the kind and physical properties of the fluid, its temperature, flow, velocity, the shape and size of the passage in which forced flow of liquid occurs.

Which dimensionless parameter is not used in fluid flow calculations?

The correct answer is option (3) Kinematic viscosity.

Why are dimensionless parameters important?

Importance of Dimensionless Numbers Dimensionless numbers help to compare two systems that are vastly different by combining the parameters of interest. For example, the Reynolds number, Re = velocity * length / kinematic viscosity.

## Which of the following is a dimensionless?

Optical density is the ratio of the speed of light in two media. As optical density is the ratio of two similar physical quantities, therefore it is the dimensionless quantity.

What are the dimensionless number associated with natural convection?

In fluid mechanics, the Rayleigh number (Ra) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free or natural convection. It characterises the fluid’s flow regime: a value in a certain lower range denotes laminar flow; a value in a higher range, turbulent flow.

What are the parameters affecting the convective heat transfer coefficient?

Convection heat transfer is treated empirically because of the factors that affect the stagnant film thickness: Fluid velocity. Fluid viscosity. Heat flux.

### What are the factors affecting convection?

Forced convection depends on the kind and physical properties of the fluid, its temperature, flow, velocity, the shape and size of the passage in which forced flow of liquid occurs.

Which of the following is not dimensionless parameter?

Is friction factor a dimensionless parameter?

The Fanning friction factor, named after John Thomas Fanning, is a dimensionless number used as a local parameter in continuum mechanics calculations.

#### Which of the following physical quantities is dimensionless?

Stress is ratio of same physical quantities hence dimensionless. Answer: Strain is ratio of two lengths , a measure of deformation – increase/decrease in length wrt original length. Thus its dimensionless , option B is correct.

Which of the following quantities ratios are dimensionless?

An angle is the ratio of two lengths i.e., arc length and radius. Therefore I is dimensionless, hence sin(i) is dimensionless.

Which of the following is dimensionless number?

Explanation: The Prandtl number is a dimensionless number. It approximates the ratio of momentum diffusivity to thermal diffusivity. It can be expressed as Pr = v/ α(1).

## What are the parameters that affect the total heat transfer coefficient in a heat exchanger?

The main parameters such as temperature of inlet and outlet working fluids, mass flow rates, pressure drops, fin design, coolants used and flow consideration.