A Caltech Library Service

Nearly free molecular flow through an orifice

Narasimha, Roddam (1960) Nearly free molecular flow through an orifice. Physics of Fluids, 3 (3). pp. 476-477. ISSN 0031-9171.

See Usage Policy.


Use this Persistent URL to link to this item:


The problem of the flow through an orifice is a very interesting one in fluid mechanics, as it promises to be one of the few configurations which can be investigated over virtually the whole range of possible motions. For this reason, Liepmann(1) has recently made measurements of the mass flow through an orifice at what are practically infinite pressure rations, through a range of Knudsen numbers covering the transition from continuum to free molecule flow. The mass flow rate per unit area in the Knudsen limit (i.e., at high K = λ1/R where λ1 is the mean free path at upstream infinity and R is the radius of the hole) is well known from kinetic theory to be m = 1/4p1c1 where p1 is the density and c1 the mean molecular speed at upstream infinity. The purpose of this note is to estimate the effect on m of a Knudsen number K that is not so large.

Item Type:Article
Related URLs:
URLURL TypeDescription
Additional Information:© 1960 American Institute of Physics. Received April 4, 1960. This work was supported by the Office of Naval Research.
Issue or Number:3
Record Number:CaltechAUTHORS:NARpof60
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8988
Deposited By: Tony Diaz
Deposited On:12 Oct 2007
Last Modified:02 Oct 2019 23:56

Repository Staff Only: item control page