Elementos finitos mixtos estabilizados para flujos viscoplásticos

• Autores: Elvira Rosa Moreno Rivero
• Directores de la Tesis: Miguel Cervera (dir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2014
• Idioma: español
• Tribunal Calificador de la Tesis: Sergio Rodolfo Idelson Barg (presid.), Antonia Larese de Tetto (secret.), Angel Herbert Owen Coppola (voc.)
• Materias:
  • Ciencias tecnológicas
    • Tecnología de la construcción
      • Ingeniería civil
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • The objective of this thesis is to develop and evaluate a methodology for the solution of the Navier-Stokes equations for Bingham Herschel-Bulkley viscoplastic fluids using stabilized mixed velocity/pressure finite elements. The theoretical formulation is developed and implemented in a computer code. Numerical solutions for these viscoplastic flows are presented and assessed. Viscoplastic fluids are characterized by minimum shear stress called yield stress. Above this yield stress, the fluid is able to flow. Below this yield stress, the fluid behaves as a quasi-rigid body, with zero strain-rate. First, the Navier-Stokes equations for incompressible fluid and two immiscible fluids considering free surface are presented. A review of the Newtonian and non-Newtonian rheological models is included, with a detailed description of the viscoplastic models. The regularized viscoplastic models due to Papanastasiou are described. Double viscosity regularized models are proposed. The analytical solutions for parallel flows are deduced for Newtonian, Bingham, and Herschel-Bulkley, pseudoplastic and dilatant fluids. The discrete model is developed, and the Algebraic SubGrid Scale (ASGS) stabilization method, the Orthogonal Subgrid scale (OSS) method and the split orthogonal subscales method are introduced. For the cases of flows with a free surface, the simplified Eulerian method is employed, with the level set method to solve the motion of the free. A convergence study is performed to compare the ASGS and OSS stabilization methods in parallel flows with Bingham and Herschel-Bulkley fluids. The double viscosity regularized models show lower convergence error convergence than the regularized models used commonly. Numerical solutions developed in this thesis are applied to a broad set of benchmark problems. They can be divided into three groups: Bingham flows, Herschel-Bulkley flows and free surface flows. The solutions obtained validate the methodology proposed in this research and com-pare well with the analytical and numerical solutions, experimental and field data. The methodology proposed in this thesis provides a computational tool to study con-fined viscoplastic flows, common in industry, and debris viscoplastic flows with free surface.