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Brazil Nut Problem and Reverse Brazil Nut Problem using the Light Scattering Method

Brazil Nut Problem and Reverse Brazil Nut Problem using the Light Scattering Method. Chaeyeon Song, Yongsoo Seo, Hyuk Kyu Pak Pusan Nat’l Univ. Order. Brazil Nut Problem (BNP) and Reverse Brazil Nut Problem (RBNP) When do BNP and RBNP occur? Experiment and control parameter

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Brazil Nut Problem and Reverse Brazil Nut Problem using the Light Scattering Method

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  1. Brazil Nut Problem and Reverse Brazil Nut Problem using the Light Scattering Method Chaeyeon Song, Yongsoo Seo, Hyuk Kyu Pak Pusan Nat’l Univ. Soft Condensed Matter Physics Lab , PNU

  2. Order • Brazil Nut Problem (BNP) and Reverse Brazil Nut Problem (RBNP) • When do BNP and RBNP occur? • Experiment and control parameter • What is the Light Scattering Method (Diffusing Wave Spectroscopy Method) ? • Experimental results • Summary Soft Condensed Matter Physics Lab , PNU

  3. BNP RBNP Brazil Nut Problem (BNP) and Reverse Brazil Nut Problem (RBNP) Brazil Nut Problem refers to the phenomenon where big particles up on the surface when a mixture of granule is vibrated vertically. Vertically vibration Soft Condensed Matter Physics Lab , PNU

  4. RBNP BNP Brazil Nut Problem Reverse Brazil Nut Problem When do BNP and RBNP occur ? • Percolation and condensation driven 2. Convection driven and Inertia driven 3. Reorganization controlled, Entropy driven, etc Soft Condensed Matter Physics Lab , PNU

  5. initiation percolation BNP RBNP Percolation and condensation process • A.P.J.Breu, H.-M.Ensner, C.A.Kruelle, and I. Rehberg(PRL. Vol 90,014302 ,2003) vibrationlowG vibrationhighG gaslike Soft Condensed Matter Physics Lab , PNU

  6. Experimental equipment Soft Condensed Matter Physics Lab , PNU

  7. Vacuum Granular vibration x(t)=Asin(2pft) Control parameter • Control Parameter Dimensionless Acceleration G=A(2pf)2/g A : amplitude g : acceleration of gravity f : frequency (50Hz) P : Pressure ( < 150mtorr ) Soft Condensed Matter Physics Lab , PNU

  8. What is the Light Scattering Method ?( Diffusing Wave Spectroscopy Method ) • Using the multiple scattering of light • Random walk (diffusing approximation) • Speckle analysis • The correlation function of DWS Speckle!! Soft Condensed Matter Physics Lab , PNU

  9. What is the Light Scattering Method? ( Diffusing Wave Spectroscopy Method) Soft Condensed Matter Physics Lab , PNU

  10. Experimental Results (3D) 6mm ball bullet( ) + 3mm glass bead( ) G= 4.58 F= 50Hz BNP initial state 6mm ball bullet ( ) + 6mm black glass bead( ) + 3mm glass bead( ) G= 4.58 F= 50Hz initial state BNP & RBNP Soft Condensed Matter Physics Lab , PNU

  11. 3mm, 4mm & 6mm glass bead (2D) G= 1.29 F= 50Hz I.3mm glass bead, relaxation time : τrelaxation≒ 82.5 μs II.4mm glass bead, relaxation time : τrelaxation≒112.2 μs III.6mm glass bead, relaxation time : τrelaxation≒170.3 μs Soft Condensed Matter Physics Lab , PNU

  12. 6mm ball bullet + 3mm glass bead (2D) τrelaxation≒38 μs τrelaxation≒345 μs Soft Condensed Matter Physics Lab , PNU

  13. 3mm glass bead + 6mm glass bead + 6mm ball bullet (3D) τrelaxation≒77 μs Soft Condensed Matter Physics Lab , PNU τrelaxation≒187 μs

  14. Summary • 브라질 땅콩 효과 는 수직 진동하는 용기 내에 두 종류의 알갱이가 섞여 있을 때 큰 알갱이가 맨 위로 올라가는 현상을 말하고 그 반대의 현상을 바로 역브라질 땅콩 효과 라고 말한다. • 이 현상에 대해 그동안 많은 연구가 행해졌으며 그 중에서 우리 실험은 percolation과 condensation 으로 설명했던 실험의 논리에 따라 실행하였다. 우리 실험에서 이 현상이 잘 재현되었고 실험 중에 나타났던 몇 가지 문제점을 해결하면서 앞으로 계속 실험해 나갈 것이다. • Light Scattering (Diffusing Wave Spectroscopy Method)을 이용하여 이 현상을 분석해보았다. Soft Condensed Matter Physics Lab , PNU

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