Numerical Modelling using SPH
Smoothed particle hydrodynamics (SPH) is a Lagrangian mesh free particle method and has significant capability in modeling the complex free surface behavior. Due to its inherit nature, SPH is suitable for modeling problems with moving interface as well as extremely large deformation. In SPH, the fluid being modeled is discretized into fluid elements or particles where the properties of the particles are attributed to their centers. The method works by tracking particles and approximating them as moving interpolation points. These fluid particles (or moving interpolation points) have a spatial distance over which field variables such as density, velocity, and energy are smoothed.
Recent application includes modeling the flow of SCC (Self Compacted Concrete) as a non-Newtonian fluid in the L-box test (Fig. 1), the V-Funnel test (Fig. 2), and the Marsh cone test (Fig. 3). . Different tests such as the Slump, L-box, and V-funnel are implemented to determine different characteristics of SCC, including its filling ability, passing ability, viscosity, and resistance against segregation. In the L-box test device, a gate is placed at the distance of L1 = 130 mm from the box back wall and the vertical part is filled with concrete. At the beginning of the test, the gate opens suddenly and the concrete flows in the horizontal part of the box, reaches the end wall and finally stops. As concrete is a non-Newtonian fluid with yield stress, its static surface will not be horizontal (unlike to the Newtonian fluid). If the ratio of the height of the concrete at the end wall (H2) to the height of the concrete at the back wall (H1) is more than 0.8, the concrete is appropriate in terms of passing and filling ability criteria and it can be considered as a self compacting concrete. SPH is capable of predicting the temporal variation of the concrete free surface level at any section of the formwork and leading edge position of the concrete (Movie 1).
Another application is the analysis of water in Tuned Sloshing Damper (TSD). TSD is a technique to minimize the vibration of the structure. It is generally a rectangular or a circular container filled with a liquid such as water and is installed at the highest level of the structure (Fig. 4). The control force is produced from the dynamic pressure acting on the side surfaces of the container, due to the oscillations of the liquid (Fig. 5, Clip 1).
Author Papers on SPH Modeling
LashkarBoluck, H., Chamani, M.R., Halabian, A.M., and Pishevar, A.R. (2012), “Simulation of water-clay flow in dam break with SPH method”, The 9th International Congress on Civil Engineering, Isfahan, Iran, May 8-10.
Lashkarbolouk, H., Chamani, M.R., Halabian, A.M., and Pishehvar, A.R. (2013), “Viscosity evaluation of SCC based on flow simulation in L-box test”, Magazine of Concrete Research, 65(6), 365–376. More details...