Flux density help please (seawater flowing in a tube)

• olibee
In summary, the flux density of salt in a horizontal tube connecting seawater (salinity = 30 g/l) to freshwater (salinity ~ 0) cannot be determined based on the given data. This can be argued using dimensional analysis and taking into account that there is no advection. It is unclear if tabulated values, such as the diffusion coefficient of salt in water, can be used in this scenario. Additionally, the equation for advective flux cannot be applied as there is no advection occurring.
olibee
Homework Statement
this is a practice problem set
Relevant Equations
I know flux = concentration x velocity but I am not quite understanding if that is applicable here
What is the flux density of salt in a horizontal tube 10 cm in length connecting seawater (salinity = 30 g/l) to a tank of freshwater (salinity ~ 0) assuming no advection occurs?

An answer cannot be given based on only the data you have given. This is easy to argue with dimensional analysis. Is this the full question as stated? Are you allowed to look up tabulated values such as the diffusion coefficient of salt in water?

And you are right. Velocity * concentration does not apply because that is based on an advective flux and it is explicitly stated that there is no advection.

What is flux density?

Flux density refers to the amount of a physical quantity, such as mass or energy, that passes through a given area in a specific amount of time. In the context of seawater flowing in a tube, flux density would refer to the amount of seawater passing through a specific cross-sectional area of the tube in a given amount of time.

How is flux density calculated?

Flux density is calculated by dividing the amount of the physical quantity passing through a given area by the time it takes to pass through that area. In the case of seawater flowing in a tube, the flux density would be calculated by dividing the volume of seawater passing through a specific cross-sectional area of the tube by the time it takes to flow through that area.

What factors affect flux density in seawater flowing in a tube?

The flux density of seawater flowing in a tube can be affected by various factors, including the velocity of the water, the diameter of the tube, and the viscosity of the seawater. Other factors such as the temperature and salinity of the seawater may also play a role in determining the flux density.

Why is flux density important in studying seawater flow?

Flux density is important in studying seawater flow because it allows scientists to understand the rate at which seawater is moving through a specific area. This information can be useful in various fields, such as oceanography, environmental science, and engineering, to better understand and predict the behavior of seawater in different conditions.

How can flux density be measured in seawater flowing in a tube?

Flux density can be measured in seawater flowing in a tube using various methods, such as using flow meters, pressure sensors, or by collecting and measuring the volume of water passing through a specific area over a given period of time. The most appropriate method will depend on the specific research or application being conducted.

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