Position based fluids

Abstract

In fluid simulation, enforcing incompressibility is crucial for realism; it is also computationally expensive. Recent work has improved efficiency, but still requires time-steps that are impractical for real-time applications. In this work we present an iterative density solver integrated into the Position Based Dynamics framework (PBD). By formulating and solving a set of positional constraints that enforce constant density, our method allows similar incompressibility and convergence to modern smoothed particle hydro-dynamic (SPH) solvers, but inherits the stability of the geometric, position based dynamics method, allowing large time steps suitable for real-time applications. We incorporate an artificial pressure term that improves particle distribution, creates surface tension, and lowers the neighborhood requirements of traditional SPH. Finally, we address the issue of energy loss by applying vorticity confinement as a velocity post process.

A unified particle system framework for multi-phase, multi-material visual simulations

“…In this scenario, we use particle boundary; to prevent particle penetration, larger viscosity and artificial viscosity are adopted. We add vorticity confinement [Fedkiw et al 2001;Macklin and Müller 2013] to make the fluid less viscous.…”

Adaptive Position-Based Fluids: Improving Performance of Fluid Simulations for Real-Time Applications

“…tively adjust the number of solver iterations for each .This allows to trade simulation precision for performance in quality results with respect to rendered evaluation itself is based on different scenarios that are mainly compared on Images from the second evaluation scenario with different methods and number of were simulated using Position Based Fluids with ܰ ൌ 5 in the bottom row based quantities, which form the basis for the computation of an .This vector is used to update the particle movement of all approach is responsible for a fairly high amount of solve the Poisson equation iteratively incompressibility. However, this is .The expensive solver , which allows for small density An alternative to WCSPH is PCISPH [12].PCISPH weakens the time-step restrictions and also achieves good results compared to WCSPH.The authors use an iterative algorithm to predict the next position and next velocity in each iteration.Ihmsen et al further improved SPH-based fluid simulation in terms of time-step restrictions and performance with IISPH [13].A recent advance in the direction of interactive and incompressible fluid simulations is the paper Position Based Fluids (PBF) by Macklin et al [4].It describes the modelling of incompressible fluids with the help of position-based constraints in the context of the Position Based Dynamics framework by [14,15].Those constraints are solved iteratively in every time step.…”

Moving particle semi-implicit method for fluid simulation with implicitly defined deforming obstacles

“…For the computation of the pressures in (2), we generate the linear system (3) using (10) and solve it at every time step.…”

“…The weakly compressible SPH [7] is an advanced method achieving nearly incompressible flow which is a key requirement for practical applications. Later studies such as the predictive-corrective incompressible SPH [8], the constraint fluids [9] and the position based fluids [10] also enforce incompressibility and has been used mainly in computer graphics. The MPS is another approach to accomplish incompressibility with high accuracy and has been successfully applied to a variety of engineering applications.…”