Improrement of the efficiency of the mixing of fluids in threedimensional flows by the use of chaos
Project/Area Number 
13650064

Research Category 
GrantinAid for Scientific Research (C)

Allocation Type  Singleyear Grants 
Section  一般 
Research Field 
Engineering fundamentals

Research Institution  Kyoto University 
Principal Investigator 
FUNAKOSHI Mitsuaki KYOTO UNIVERSITY Graduate school of informatics, Professor, 情報学研究科, 教授 (40108767)

CoInvestigator(Kenkyūbuntansha) 
KANEKO Yutaka KYOTO UNIVERSITY Graduate school of informatics, Research Associate, 情報学研究科, 助手 (00169583)

Project Period (FY) 
2001 – 2003

Project Status 
Completed (Fiscal Year 2003)

Budget Amount *help 
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)

Keywords  Mixing / Chaos / Threedimensional flow 
Research Abstract 
As an example of the static mixers that are typical mixing devices, a model of partitionedpipe mixer (PPM) was considered which is composed of axially periodic pairs of plane plates of a definite angle within an infinitely long rotating cylinder. The following results were obtained by the examination of the chaotic motion of fluid elements and the efficiency of the mixing due to an approximate velocity field that is composed of the velocity field for an infinitely long plane plate and a transient velocity field: (1) The efficiency of the mixing can be improved by the generalization of the PPM model in which the ratio a of the lengths of a pair of plane plates can be changed from one, and the angle between these plates can be changed from 90 degree. (2) Poincare sections are not sufficient as the index of the efficiency of the mixing in a few. axial periods. Lines of separation U(n), the set of crosssectional initial locations of fluid particles that move to one of the leading edges o
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f the plates within n periods, can be used as the index of the mixing in n periods. That is, if the region where U(n) is distributed densely is large, the efficient mixing is expected. Next, from the numerical computation of the exact velocity field in PPM, it was found that this velocity field has the reverseflow region for a small axial pressure gradient and is considerably different from the approximate velocity field. From the Poincare sections based on the exact velocity field, the following results were obtained: (1) The regular region can be reduced by changing a to appropriate values, similarly to the result for the approximate velocity field. (2) U(n) can be introduced even for the exact velocity field. Efficient mixing is expected if the region where U(n) is distributed densely is large. From the computation of the largest stretching rate of fluid line elements in the crosssectional direction in their axial motion by a definite period, it was found that the line elements starting near the lines of separation are strongly stretched and that this strong stretching mainly contributes to the efficient mixing in PPM. Less

Report
(4 results)
Research Products
(10 results)