Simulations on diffusion and transport phenomena ・phenomena ‐ Examples for transport and diffusion phenomena ‐ Discuss about the common characteristics and nature among these examples ・physical models ‐ Explain to the mathematical model about Brownian motion, turbulent diffusion, and turbulence transport ・numerical simulations ‐ Examples for simulating one‐particle diffusion, thermal convection, and passive scalar turbulence Field of computational applied science T. Watanabe
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Simulations on diffusion and transport phenomena
・phenomena‐ Examples for transport and diffusion phenomena‐ Discuss about the common characteristics and nature among these examples
・physical models‐ Explain to the mathematical model about Brownian motion, turbulent diffusion, and turbulence transport
・numerical simulations‐ Examples for simulating one‐particle diffusion, thermal convection, and passive scalar turbulence
Field of computational applied science T. Watanabe
Homework (report) 1.Mention about the example of transport and diffusion phenomena
that you can observe at your ordinal life, engineering system, etc. Then explain about their characteristics by using the mathematics, pictures, painting, and so on.
2.Discuss about the importance and significance when the numerical simulations for examples mentioned in 1. are performed.
・using A4 size paper and summarizing within 1~2 sheets・making cover sheet and state your student number , nameand the date of submission・site for submission: 2号館4階422B室 (insert in the box)・deadline for submission July, 3(Fri.) 17:00
3.Please give your thoughts on this lecture.
Examples on transport and diffusion phenomena
• pollutant diffusion• come flying volcanic ash, yellow dust • water vapor, thermal (cloud physics)• thermal transport • combustion• chemical reaction flow• ・・・
http://www.nsc.go.jp/mext_speedi/index.html
緊急時迅速放射能影響予測ネットワークシステム(System for Prediction of Environmental Emergency Dose Information, SPEEDI)
Outflow and diffusion of a radioactive substance from a nuclear power plant at Fukushima
Complicated physical system interacting between fluid and particles with thermal transport
・ motions of air and vapor (fluid equations)・ variation of temperature (thermodynamics eq.)・ growth of droplets, deformation, merging, splitting(motions for ensemble of particles)
distribution of Temperature (T), salinity (S) inside the sea (normal direction)
104.0 CmT 101.0 mkggS
Schmit number ,Plandle number
CS
310OSC
10~1 OOPr : heat
: salinity
Passive scalar: Any motions of scalar quantitydoes not affect to fluid motions
Passive scalar under uniform mean gradient
TκTtT 2 uAdvection – diffusion eq.
Fluctuation of does not affect to fluid motion tθ ,x
Scalar field
mean gradient
xGxx tθtT ,,
G,0,0G
32 Guθκθ
tθ
u
T
z
fluctuation
計算機A 計算機B
計算機D 計算機C
Image of parallel computation
Large-scale simulationParallel computation by using 「supercomputer」
A B
D C
「Kei」 ( CCP2012,Kobe )
Large-scale simulation for turbulent transport
Mixing by turbulent vortices
103 102048 NGrid points:
Process numbers: pe=128
Total memory:2TB(=2000GB)
Computation time:5000(h)=208days
Buoyancy term=0
Vortical structures (green) and temperature sheets(blue)
Visualization of numerical results of turbulent transport
vorticity(z)(color) and scalar gradient (x‐y plane)(black)
Visualization of numerical results of turbulent transport
Structures in 2D slice
x
z
zx ,,
・z-direction
・x-direction
-1
263Rcase G
海上保安庁海洋情報部 http://www1.kaiho.mlit.go.jp/
distribution of temperature at sea surface
44
2D slice by 20483 DNS
2
0,, yx
L
45
L
5
2D slice by 20483 DNS 0,, yx
46
905
10
2D slice by 20483 DNS 0,, yx
Summary of lecture• Physics of transport and diffusion phenomena
‐Mathematical models of particle motion in fluid and its numerical simulations‐Model for heat and mass transfer in turbulent flow(Simulations for scalar field advected by fluid motion)
• Diffusion of the ensemble of particles by turbulence(molecular diffusion vs. Turbulent diffusion)
• Heat transfer by turbulence(cliff structures in temperature field, correlation with vortices )
Effective use of the transfer ability of turbulence Diffusion properties by turbulece
Importance for better understanding of the flow properties
Application for constructing more reliable simulation models (weather prediction, pollutant diffusion)
Homework (report) 1.Mention about the example of transport and diffusion phenomena
that you can observe at your ordinal life, engineering system, etc. Then explain about their characteristics by using the mathematics, pictures, painting, and so on.
2.Discuss about the importance and significance when the numerical simulations for examples mentioned in 1. are performed.
・using A4 size paper and summarizing within 1~2 sheets・making cover sheet and state your student number , nameand the date of submission・site for submission: 2号館4階422B室 (insert in the box)・deadline for submission July, 3(Fri.) 17:00