Question

Can someone help me with this question.

Briefly explain the following terms:

1. Plug flow of a pollutant in a river

2. Building Downwash

3. Length of lateral mixing

4. Seepage velocity

5. Shear Velocity

Answer 1

The length of lateral mixing is the distance a that a fluid parcel will keep its original characteristics before dispersing them into the surrounding fluid • It is also known as Prandtl's mixing length Id, after Ludwing Prandt/ who devised - it in 1925 to explain turbulent fluxes 4 Seepage velocity - It is the velocity of groundwater calculated from Darcy's. law. Seepage velocity is not the actual velocity of the water in the pores, but the apparent velocity through the bulk of the porous medium. Actual velocity is higher than geepage velocity by a factor which combines the effects of porosity and the tortuosity of the actual flow path among and around the mineral grains Shear velocity. It is also called frichon velocity is a form by which a shear stress may be rewritten in units of velocity. It is useful as a method in fluid mechanics to compare true velocities, such as the velocity of a flow in a stream to a velocity that relates shear between layers of flow. It is used to describe shear related motion in moving fluids.

D Plug flow of pollutant in a river - - In fluid mechanics plug flow is a simple model of the velocity profile of a fluid flowing in a pipe. In plug flow, the velocity of the fluid is assumed to be constant across any cross-section of the pipe perpendicular to the axis of the pipe. "Hooding stream directly influenced by Stream flow and runoff and stream flow ' drive the generation transport many non- point source pollutant are flow in the river which is calculated by knowledge of water flow. 2) Building down wash - The presence of building can affect plume rise and the initial dispersion of pollutants within the atmosphere Turbulent wake cones can be created around buildings that force pollutants within th to the ground instead of allowing them to rise within the atmosphere. Building downwash. occurs as the wind flows over and around buildings and impacts the dispersion of pollution from nearby stacks ret