Final answer:
A velocity profile in forced convection heat transfer with laminar flow over a flat plate starts at zero velocity at the plate surface due to the no-slip condition, and the velocity increases with distance from the plate until it reaches the constant free stream velocity.
Step-by-step explanation:
The question relates to the visualization of a velocity profile in the context of forced convection heat transfer when a fluid flows over a flat plate. In forced convection, fluid motion is driven by external means, such as a pump or a fan. One common example of forced convection is fluid flowing over a plate.
When considering laminar flow of a fluid over a flat plate, the velocity profile can be depicted as a gradient from the plate surface to the free stream. Near the plate surface, the velocity of the fluid is zero due to the no-slip condition. This is where the fluid is in direct contact with the solid boundary (the plate), and the adhesive forces cause the fluid to stick to the surface (v = 0).
As you move away from the plate, the velocity of each successive layer of fluid increases because each layer is being dragged along by the one above it. At the very top of the boundary layer, the fluid moves at its free stream velocity.
This profile can be represented graphically with velocity on the y-axis and the distance from the plate on the x-axis. Starting from the plate, the curve rises sharply, indicating increasing velocity, and then flattens out as it approaches the free stream velocity, which is constant for layers of fluid far removed from the influence of the plate.