particles in high pressure air always flow to lower pressure. In a pipe with a constriction, fluid flows from from low to high pressure after the constriction.

The Short Answer: Gases move from high-pressure areas to low-pressure areas. And the bigger the difference between the pressures, the faster the air will move from the high to the low pressure. That rush of air is the wind we experience.

Pressure is the cause. Flow rate is the effect. Higher pressure causes increased flow rate. If the flow rate increases, it is caused by increased pressure.

Fluid basically flows from “higher energy level” to a “lower energy level”. And yes, fluid can flow from low pressure point to high pressure point .

Pressure Change due to Velocity Change If the flow area increases through an expansion or diffuser, the velocity will decrease and result in an increase in the static pressure. If the pipe diameter is constant, the velocity will be constant and there will be no change in pressure due to a change in velocity.

Because water is denser than air, water exerts more pressure than air does. Fluids flow from areas of high pressure to areas of low pressure.

Areas of high and low pressure are caused by ascending and descending air. As air warms it ascends, leading to low pressure at the surface. As air cools it descends, leading to high pressure at the surface.

The reason pressure changes lead to movement is Newton’s law of motion— a pressure is a flow of momentum from one place to another. Momentum always shows up as bulk motion of the center of mass. Momentum is a conserved quantity, and it moves from place to place, like charge, always keeping the total constant.

In a high pressure zone, particles experience a high force, and in a low pressure zone, they experience a lower force. The high force “overpowers” the lower force, pushing the particles from the high pressure zone to the lower pressure zone.

Pressure and flow are related to each other, as pressure difference being the cause of the flow. When a pressure difference between two points exists within a fluid and is not balanced out by the internal forces acting on the body, the fluid start to move from the higher pressure point to the low pressure point to minimize the pressure difference.

When plotted on a graph, the relationship between flow rate (Q) and differential pressure (ΔP) is quadratic , like one-half of a parabola. Differential pressure developed by a venturi, orifice plate, pitot tube, or any other acceleration-based flow element is proportional to the square of the flow rate: Differential Pressure Flow Meters

Pascal’s principle states that pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid, as well as on the walls of the container. Therefore, pressure remains unchanged, but force on the particles of the fluid do, depending on the cross-sectional area of your container.

The point is, force is not the flux of pressure because it’s exerted in ALL directions. No matter how the element is oriented, the pressure is the same scalar function of distance from the centre.