1 / 25

Sloshing liquid in a rectangular tank

kristian
Download Presentation

Sloshing liquid in a rectangular tank

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Sloshing liquid in a rectangular tank Pawel Zimoch ES 240 Fall 2008

    2. Motivation Great practical importance, especially in transport (tankers, trucks) Personal interest

    3. Initial goals Simulate vibrations of coffee in a mug Cylindrical tank Newtonian fluid Horizontal harmonic forcing Expected result:

    4. Software Chose COMSOL due to advice COMSOL supports moving mesh which allows modeling of free fluid surfaces A basic sloshing liquid model exists in the built in model library

    5. COMSOLs basic model Response of a body of fluid under rotation of the gravity vector Rectangular subdomain Fluid modeled using incompressible Navier-Stokes equations Liquid: glycerol Denisty: 1270 kg/m^3 Dynamic viscosity: 1.49 Pa s

    6. Subdomain Geometry

    7. Boundary Conditions Sides and bottom: slip/symmetry Normal component of velocity =0 Tangential component of viscous force = 0 Top: neutral Total force = 0 (free boundary)

    8. Boundary Conditions Sides: constrained in x-direction Bottom: constrained in x and y-direction Top: mesh follows deformations of the liquid Velocity of the mesh in the direction parallel to its normal equals the velocity of the fluid

    9. Modeling approach Adopt similar boundary conditions to 3D geometry Failed In cylindrical coordinates system was underdetermined In rectangular coordinates, solver could not handle the constraints (freeze) Therefore, decided to model in rectangular 2D, investigate

    10. Physical situation Constant horizontal acceleration 1m/s^2 for 2 seconds, then release E.g breaking of a truck with a fluid tank Find out: Extreme positions of vertical boundaries Pressures on the walls Total force on the tank

    11. Result

    12. Total horizontal force

    13. Displacement of liquid on vertical boundaries Right boundary

    14. Pressure on walls Right Bottom (x=0) Middle (x=0.15) Top (x=0.3) 40% reduction in pressure from x=0.15 to x=0 (statically 50%)

    16. Is the model accurate? Fluid is glycerol very viscous The vibrations experience almost no damping. Energy should be dissipated due to viscous friction model does not represent physics accurately Solution try to implement no-slip boundary condition

    17. Model with no-slip boundary conditions Model vertical and bottom boundary as no-slip. Top boundary remains neutral. Result:

    18. Finer mesh

    19. Very fine mesh

    20. Less viscous fluid

    21. Conclusions While the model seems to show general behavior of a fluid well, its much worse at representing a given fluid To accurately represent viscous fluids, no-slip boundary condition must be possible to enforce.

    22. Interesting failures (1)

    23. Interesting failures (2)

    24. Acknowledgments

    25. Questions?

More Related