SHe = (8.0±0.3)x10-7s-1m3 SAr = (5.7±0.3)x10-7s-1m3

The main objective within this report is to investigate the properties of laminar and molecular gas flow through narrow tubes by experiment.

In laminar flow the gas is in a steady state, moving smoothly through the tube. At any point in the tube the velocity remains constant, although neighbouring layers of gas are moving at different speeds.

In molecular flow the gas is in a state of low pressure. Collisions of the gas molecules are almost all with the walls of the tube rather than with neighbouring molecules.

In the experiment the rates of flow two inert (monatomic) gases helium and argon will be observed. The rate of flow of gas is a large-scale or macroscopic quantity and can easily be measured in a laboratory by observing pressure changes. This can be related to the microscopic properties of the gases.

During laminar flow the layers within the gas are moving at different speeds. In the middle of the tube the a

· It is then filled to a pressure of 10mbar Helium using the inlet at A.

Plotting against time should therefore produce a straight line whose gradient (m) is given by . Rearranging gives .

toms are moving faster and at the edge of the tube the speed decreases parabolically to zero. The differing speeds cause a shearing force in the gas, which is described by a coefficient of viscosity (h). The following Poiseuille’s equation describes the rate of flow of gas through a tube (Q) with one end at pressure p1 and the other at a lower pressure p0.

This procedure is repeated for Argon.

Some topics in this essay:
Mcleod Gauge, Laminar Flow, Helium Argon, Flow Molecular, Tubes Abstract, Finding Reynolds, Due Helium, Flow Helium, Flow Argon, Experimental Method, laminar flow, molecular flow, mean free path, free path, mean free, coefficient viscosity, collision cross-section, gas flow, pumping speed, narrow tube, flow helium, pumping speed tube, molecular gas flow, laminar molecular gas, properties laminar molecular,