Simulation of Magnetorheological Fluid Flows at Particle Scale

Hashemi, Mohammad Reza; Taghizadeh Manzari, Mehrdad Fatehi, Rouhollah

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Simulation of Magnetorheological Fluid Flows at Particle Scale

Hashemi, Mohammad Reza | 2018

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Type of Document: Ph.D. Dissertation
Language: Farsi
Document No: 50472 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Taghizadeh Manzari, Mehrdad; Fatehi, Rouhollah
Abstract:
Magnetorheological fluids are suspensions of magnetic solid particles suspended in a nonmagnetic matrix fluid. By imposing an external magnetic field, particles are arranged in microstructures aligned with the external field and hence, dramatically affect the fluid flow. Since the strength of the magnetic field determines the resistance of these microstructures against flow, the rheology of the suspension is a function of the intensity of the external magnetic field. The goal of the present work is to study the role of non-gap-spanning magnetic clusters on the rheology of a magnetorheological fluid. Here, first a robust tool for direct numerical simulation of magnetic suspensions is introduced. The method is developed within the framework of Smoothed Particle Hydrodynamics (SPH). Investigating the numerical instability of the weakly-compressible SPH method, a pressure-splitting formulation is proposed and its capability in the suppression of the spurious pressure oscillations is shown. Moreover, the equations governing the magnetic field are discretized using the renormalized SPH derivative schemes and solved for the whole fluid-solid domain. The accuracy of the proposed method in calculating the magnetic interaction between solid particles and its capability in simulating magnetic suspensions are investigated. In the second part of this work, simulations are performed for non-gap-spanning magnetic clusters suspended in a Newtonian fluid and the rheology of the model magnetic suspension is studied in steady and oscillatory shear tests. In small amplitude oscillatory shear tests, the viscoelasticity of the suspension is highlighted and the effects of inertia on the measured rheological parameters are studied. Then, the nonlinear stress response of the suspension is investigated in large amplitude oscillatory shear tests
Keywords:
Rheology ; Smoothed Particle Hydrodynamics (SPH) ; Magnetorheological (MR)Fluid ; Flow Simulation ; Oscillatory Shear

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10.1016@j.camwa.2015.12.034.pdf
- Evaluation of a pressure splitting formulation for Weakly Compressible SPH: Fluid flow around periodic array of cylinders
  - Introduction
  - Numerical method
    - Renormalization
    - Pressure--velocity coupling
    - Remarks
  - Stability analysis
    - Verification
  - Results: start-up flow around a periodic array of cylinders
    - Validation and convergence
      - Vanishing reynolds Reynolds number
      - Moderately low Reynolds number
    - The effects of artificial speed of sound
      - Vanishing Reynolds number
      - Moderately low Reynolds number
  - Conclusion
  - Acknowledgement
  - Numerical algorithm
  - Effects of a predictor--corrector
  - References
10.1016@j.apm.2015.11.020.pdf
- A SPH solver for simulating paramagnetic solid fluid interaction in the presence of an external magnetic field
  - 1 Introduction
  - 2 Governing equations
    - 2.1 Hydrodynamics
    - 2.2 Magnetostatics
  - 3 Smoothed particle hydrodynamics
    - 3.1 Implementation
    - 3.2 Moving solid bodies
    - 3.3 Magnetic force
    - 3.4 Stabilized SPH method
      - 3.4.1 Modified continuity equation
      - 3.4.2 SPH particle shifting
    - 3.5 Remarks
  - 4 Results
    - 4.1 Magnetic force verification
    - 4.2 Test problems
      - 4.2.1 A single solid body in a closed cavity
      - 4.2.2 Momentum conservation
      - 4.2.3 A pair of solid bodies in a cosed cavity
      - 4.2.4 Magnetic chain in a rotating magnetic field
    - 4.3 Application: magnetic chain in a periodic shear flow
      - 4.3.1 Effect of solid volume fraction
      - 4.3.2 Effect of mason number
      - 4.3.3 Small amplitude oscillatory shear
  - 5 Conclusion
  - Acknowledgment
  - Appendix A Magnetic force density
  - Appendix B Numerical algorithm
  - Appendix C The finite element method
  - References
10.1016@j.camwa.2015.12.034.pdf
- Evaluation of a pressure splitting formulation for Weakly Compressible SPH: Fluid flow around periodic array of cylinders
10.1016@j.apm.2015.11.020.pdf
- A SPH solver for simulating paramagnetic solid fluid interaction in the presence of an external magnetic field

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