The pressure difference is increasing, there is a reason and which particularly in this part you see that the flow distribution is in the negative direction that means fluid flow in the opposite direction. There is a chance that, chance that flow direction can be negative, can be negative. The fluid flow is in the opposite direction and what does it means because that means the viscosity is dragging the drag the motion and there is a situation which makes the flow to be in the positive direction.
It is due to the basically, this is the due to the adverse pressure gradient, which is due to adverse pressure gradient which surfaces the dragging action for the faster layer of the fluid which surfaces adverse pressure gradient which surfaces the dragging action of the faster layer of the fluid particle. So, these are the three cases where in one case in this case particularly this is one of the interesting observation that the flow can be in the negative direction and this is the only possible when we have this particularly in the presence of a vicious drag with difference in pressure.