Introducing CHAD -- An ADM1 Solver for Direct Linking to Lagrangian CFD Software

Standard methods for modeling anaerobic digestion processes assume homogeneous conditions inside the tank and thus suffer from the negligence of hydrodynamics. In this work, we present the software toolbox Coupled Hydrodynamics and Anaerobic Digestion (CHAD), a novel parallelized solver that is capable of utilizing CFD results as the basis for Anaerobic digestion model No.1 (ADMno1) simulations. CHAD uses a particle-based Lagrangian CFD solver i.e., DualSPHysics (DSPH) as input and provides for a parallelized, C++ code implementation of the standard ADMno1. This paper demonstrates a conceptual and numerical verification of the toolbox and outlines the future pathway to enhance the approach.Comment: conference pape

Smoothed particle hydrodynamics for blood flow analysis: development of particle lifecycle algorithm

The aim of this research was to facilitate the application of Smoothed Particle Hydrodynamics (SPH) method to Computational Fluid Dynamics analysis of turbulent flow through complex geometry blood vessels, and to compare it with the state-of-the-art Finite Element Method (FEM). SPH offers the possibility to observe motion of fluid fragment or particle inclusion within the Lagrangian material framework, giving researchers greater insight into the Fluid-Structure interaction such as transportation and distribution of medical particles, or buildup of plaque in atherosclerosis. In order to generate the fluid flow in SPH, the particles are created at inlet, and destroyed at the outlet. In this paper we present a novel lifecycle algorithm for generation and destruction of the particles using particle types, which is more flexible and suitable for the complex geometry models in comparison to the current state of the art commercial solutions, which use boundary planes. Our algorithm features mother and new-born particle types located at inlets used for the particle flow generation, and at the outlets, we have dying and killer particle types, which are used for deletion of particles. Based upon the current neighbors, the type of the particle is updated within the nearest neighbor search method, which is invoked in each time step. The capabilities of the new algorithm are demonstrated using a benchmark example and a realistic patient specific geometry, showing similar results, but the SPH advantages of particle tracking are yet to be utilized in our future work.Ministry of Education, Science and Technological Development of the Republic of SerbiaPublishe

DualSPHysics: from fluid dynamics to multiphysics problems

DualSPHysics is a weakly compressible smoothed particle hydrodynamics (SPH) Navier–Stokes solver initially conceived to deal with coastal engineering problems, especially those related to wave impact with coastal structures. Since the first release back in 2011, DualSPHysics has shown to be robust and accurate for simulating extreme wave events along with a continuous improvement in efficiency thanks to the exploitation of hardware such as graphics processing units for scientific computing or the coupling with wave propagating models such as SWASH and OceanWave3D. Numerous additional functionalities have also been included in the DualSPHysics package over the last few years which allow the simulation of fluid-driven objects. The use of the discrete element method has allowed the solver to simulate the interaction among different bodies (sliding rocks, for example), which provides a unique tool to analyse debris flows. In addition, the recent coupling with other solvers like Project Chrono or MoorDyn has been a milestone in the development of the solver. Project Chrono allows the simulation of articulated structures with joints, hinges, sliders and springs and MoorDyn allows simulating moored structures. Both functionalities make DualSPHysics especially suited for the simulation of offshore energy harvesting devices. Lately, the present state of maturity of the solver goes beyond single-phase simulations, allowing multi-phase simulations with gas–liquid and a combination of Newtonian and non-Newtonian models expanding further the capabilities and range of applications for the DualSPHysics solver. These advances and functionalities make DualSPHysics an advanced meshless solver with emphasis on free-surface flow modelling

Neighbour lists for smoothed particle hydrodynamics on GPUs

The efficient iteration of neighbouring particles is a performance critical aspect of any high performance smoothed particle hydrodynamics (SPH) solver. SPH solvers that implement a constant smoothing length generally divide the simulation domain into a uniform grid to reduce the computational complexity of the neighbour search. Based on this method, particle neighbours are either stored per grid cell or for each individual particle, denoted as Verlet list. While the latter approach has significantly higher memory requirements, it has the potential for a significant computational speedup. A theoretical comparison is performed to estimate the potential improvements of the method based on unknown hardware dependent factors. Subsequently, the computational performance of both approaches is empirically evaluated on graphics processing units. It is shown that the speedup differs significantly for different hardware, dimensionality and floating point precision. The Verlet list algorithm is implemented as an alternative to the cell linked list approach in the open-source SPH solver DualSPHysics and provided as a standalone software package

Proof of a locally limited imperfection of the diaphragm wall based on the numerical method Smoothed-Particle Hydrodynamics (SPH)

In dieser Dissertation werden die Fehlstellen in den Schlitzwänden untersucht und numerisch simuliert. Die Simulation erfolgt auf Basis des numerischen Verfahrens „Smoothed Particle Hydrodynamics (SPH)“. Die SPH-Methode ist ein gitterfreies Verfahren, das ursprünglich zur numerischen Simulation der astronomischen Probleme erfunden wurde. Diese Methode wurde in den letzten zehn Jahren auch häufig bei geotechnischen Problemen angewendet, insbesondere bei Problemen mit großen Verformungen, die mit herkömmlichen gitterbasierten Methoden wie der Finite-Elemente-Methode sehr schwierig und kompliziert zu simulieren sind. In dieser Forschungsarbeit wurde ein Fortran-Code zur Simulation der Imperfektionen in Schlitzwänden mit der SPH-Methode entwickelt. Um diesen Code zu validieren, werden verschiedene geotechnische Probleme modelliert und die Ergebnisse mit den verschiedenen bekannten Experimenten verglichen. Darüber hinaus wurde früher im Institut für Geo-Engineering der Technischen Universität Clausthal eine Serie von Experimenten durchgeführt, um den Einsturz des historischen Archivgebäudes der Stadt Köln in Deutschland zu erforschen. Auch dieser Versuch wird mit dem entwickelten Fortran-Code simuliert, um die Fähigkeit der SPH-Methode zur Simulation der Imperfektionen in Schlitzwänden auch bei hohem Grundwasserspiegel nachweisen zu können.In this dissertation, the imperfections of diaphragm walls are investigated and numerically simulated. The simulation is carried out based on a numerical method “Smoothed Particle Hydrodynamics (SPH)”. The SPH method is a meshfree method, which is originally invented for numerical simulation of the astronomical problems. This method is also often applied in the last decade in the geotechnical problems, especially the problems with large deformations, which are very difficult and complicated to simulate in the conventional grid-based methods as like as Finite Element method. In this research, a Fortran-Code for simulation of the imperfections in diaphragm walls with SPH method is developed. To validate this code, various geotechnic problems are modelled and the results compared with the different known experiments. Furthermore, an Experiment is carried out earlier in the Institute of Geo Engineering in Technical University of Clausthal in order to observe the collapse of the historical archive building of the city Cologne in Germany. This experiment is also with the developed Fortran-Code simulated, to present the capabilities of the SPH method for simulating the imperfections in diaphragm walls even with high groundwater level