02 Transport Phenomena part 2

What is the formula for total flux?

• Total flux = Characteristic velocity x Characteristic length

• Total flux = Diffusivity x Gradient of quantity volume

• Total flux = Mass flow rate + Mole flow rate

• Total flux = Molecular flux + Convective flux

What does the Peclet number (Pe) indicate?

• The mass of a substance

• The velocity of a fluid

• The total energy in a system

• The ratio of convective to diffusive transport

What is the formula for convective flux?

• Convective flux = Characteristic velocity x (quantity/volume)

• Convective flux = Diffusivity x (gradient of quantity/volume)

• Convective flux = Characteristic velocity x (gradient of quantity/volume)

• Convective flux = Diffusivity x (quantity/volume)

When is total flux equal to convective flux?

• When Pe ≈ 1

• When Pe = 0

• When Pe << 1

• When Pe >> 1

What happens when Pe << 1?

• Total flux equals molecular flux

• Total flux equals convective flux

• Total flux is undefined

• Total flux is zero

What is the role of thermal diffusivity in energy transport?

• It measures how quickly energy spreads through a material

• It determines the total energy in a system

• It measures the velocity of a fluid

• It calculates the mass flow rate

What is the formula for the rate of energy entering a system if Pe<<1?

• Ė = Density x Velocity

• Ė = Mass flow rate x Energy content

• Ė = Thermal diffusivity x Gradient of energy / Volume

• Ė = Energy / Volume

What does the term 'convective energy flux' refer to?

• The energy carried by the bulk movement of a fluid

• The energy lost through radiation

• The energy stored in a system

• The energy transferred by conduction

What is the relationship between mass flow rate and mole flow rate?

• Mass flow rate = Concentration x Flow Area

• Mass flow rate = Energy flow rate / Flow Area

• Mass flow rate = Mole flow rate x Volume

• Mass flow rate = Density x Velocity x Flow Area

What is the effect of Pe ≈ 1 on total flux?

• Total flux is influenced equally by both molecular and convective flux

• Total flux is only convective

• Total flux is negligible

• Total flux is only molecular