On Efficiency of the OpenFOAM-based Parallel Solver for the Heat Transfer in Electrical Power Cables

Proceedings of: First International Workshop on Sustainable Ultrascale Computing Systems (NESUS 2014). Porto (Portugal), August 27-28, 2014.In this work, we study the efficiency of the OpenFOAM-based parallel solver for the heat conduction in electrical power cables. The 2D benchmark problem with three cables is used for our numerical tests. We study and compare the efficiency of conjugate gradient solver with diagonal incomplete Cholesky (DIC) preconditioner and generalized geometric algebraic multigrid solver (GAMG), which is available in Open- FOAM. The convergence and parallel scalability of the solvers are presented and analyzed. Parallel numerical tests are performed on the cluster of multicore computers.The work of authors was supported by Eureka project E!6799 POWEROPT "Mathematical modelling and optimization of electrical power cables for an improvement of their design rules". The work presented in this paper has been partially supported by EU under the COST programme Action IC1305, ’Network for Sustainable Ultrascale Computing (NESUS)’

The Investigation of Efficiency of Physical Phenomena Modelling Using Differential Equations on Distributed Systems

This work is dedicated to development of mathematical modelling software. In this dissertation numerical methods and algorithms are investigated in software making context. While applying a numerical method it is important to take into account the limited computer resources, the architecture of these resources and how do methods affect software robustness. Three main aspects of this investigation are that software implementation must be efficient, robust and be able to utilize specific hardware resources. The hardware specificity in this work is related to distributed computations of different types: single CPU with multiple cores, multiple CPUs with multiple cores and highly parallel multithreaded GPU device. The investigation is done in three directions: GPU usage for 3D FDTD calculations, FVM method usage to implement efficient calculations of a very specific heat transferring problem, and development of special techniques for software for specific bacteria self organization problem when the results are sensitive to numerical methods, initial data and even computer round-off errors. All these directions are dedicated to create correct technological components that make a software implementation robust and efficient. The time prediction model for 3D FDTD calculations is proposed, which lets to evaluate the efficiency of different GPUs. A reasonable speedup with GPU comparing to CPU is obtained. For FVM implementation the OpenFOAM open source software is selected as a basis for implementation of calculations and a few algorithms and their modifications to solve efficiency issues are proposed. The FVM parallel solver is implemented and analyzed, it is adapted to heterogeneous cluster Vilkas. To create robust software for simulation of bacteria self organization mathematically robust methods are applied and results are analyzed, the algorithm is modified for parallel computations

On economic-technological optimization of high-voltage electric cables

In this paper, mathematical modelling of high voltage cables for power transmission line design is presented. The Finite Volume Method (FVM) is used to approximate the developed mathematical model (a system of nonlinear multi-physic differential equations) and OpenFOAM (Open source Field Operation And Manipulation) tool is used to implement the obtained parallel finite volume schemes. In order to optimize the design of power lines with respect to technological parameters, different cases of nonstationary load dynamics are investigated and the influence of system nonlinearity and external day, month and years periodical boundary conditions and the source function regimes are simulated. The main aim of this paper is to include into the mathematical model also economic requirements and to optimize sizes of cables with respect to both technologic and economic requirements. Numerical algorithms targeted to solve PDE-constrained optimization problems are developed. Results of computational experiments are presented

On economic-technological optimization of high-voltage electric cables

In this paper, mathematical modelling of high voltage cables for power transmission line design is presented. The Finite Volume Method (FVM) is used to approximate the developed mathematical model (a system of nonlinear multi-physic differential equations) and OpenFOAM (Open source Field Operation And Manipulation) tool is used to implement the obtained parallel finite volume schemes. In order to optimize the design of power lines with respect to technological parameters, different cases of nonstationary load dynamics are investigated and the influence of system nonlinearity and external day, month and years periodical boundary conditions and the source function regimes are simulated. The main aim of this paper is to include into the mathematical model also economic requirements and to optimize sizes of cables with respect to both technologic and economic requirements. Numerical algorithms targeted to solve PDE-constrained optimization problems are developed. Results of computational experiments are presented

Proceedings of the First PhD Symposium on Sustainable Ultrascale Computing Systems (NESUS PhD 2016)

Proceedings of the First PhD Symposium on Sustainable Ultrascale Computing Systems (NESUS PhD 2016) Timisoara, Romania. February 8-11, 2016.The PhD Symposium was a very good opportunity for the young researchers to share information and knowledge, to present their current research, and to discuss topics with other students in order to look for synergies and common research topics. The idea was very successful and the assessment made by the PhD Student was very good. It also helped to achieve one of the major goals of the NESUS Action: to establish an open European research network targeting sustainable solutions for ultrascale computing aiming at cross fertilization among HPC, large scale distributed systems, and big data management, training, contributing to glue disparate researchers working across different areas and provide a meeting ground for researchers in these separate areas to exchange ideas, to identify synergies, and to pursue common activities in research topics such as sustainable software solutions (applications and system software stack), data management, energy efficiency, and resilience.European Cooperation in Science and Technology. COS

Proceedings of the First International Workshop on Sustainable Ultrascale Computing Systems (NESUS 2014): Porto, Portugal

Proceedings of: First International Workshop on Sustainable Ultrascale Computing Systems (NESUS 2014). Porto (Portugal), August 27-28, 2014

On Efficiency of Parallel Solvers for the Blood Flow through Aortic Valve

Mathematical modelling of cardiac haemodynamics presents a great challenge to the computational scientists due to numerous numerical issues and required computational resources. In this paper, we study the parallel performance of 3D simulation software for the blood flow through the aortic valve. The fluid flow problem with the open aortic valve leaflets is formulated and solved in parallel. The choice between the segregated and coupled numerical schemes is discussed and investigated. We present and compare the parallel performance results of both types of parallel solvers. We investigate their strong and weak scalability

Numerical Simulation of the Lux Vertical Axis Wind Turbine

Wind energy can be characterized as a cheap, clean, and renewable energy source that is absolutely sustainable. With increasing demand for wind energy, it is productive to investigate the structural and operational factors that undermine the proficiency and the characteristic performance of the wind turbine. Of paramount importance to efficient wind energy generation is the aerodynamics of the wind turbine blades. The aerodynamic factors, such as drag, airfoil pro files, and wake interactions that often reduce the performance of the wind turbines, can be investigated through computational mathematics using computational fluid dynamics (CFD). CFD offers basic techniques and tools for simulating physical processes and proffers important insights into the ow data, which are demanding and costly to measure experimentally. In this thesis, we develop a simulation model in an open-source software package called OpenFOAM to investigate the performance characteristics of the Lux Vertical Axis Wind Turbine (VAWT). The Lux VAWT has a simpler design than its horizontal counterparts; however, its performance is affected by the unsteady aerodynamic due to a complex flow field. The turbulent flow field is governed by the incompressible Navier- Stokes equations. Simulations are carried out with an unsteady incompressible and dynamic flow solver, PimpleDyMFoam, on an unstructured mesh surface of the Lux VAWT geometry. The computational domain includes both the stationary and rotating mesh domains to accommodate the rotating motion of the turbine blades and the free-stream zone. The arbitrary mesh interface is applied as a boundary condition for the patches between the two domains to enable computation across disconnected but adjacent mesh domains. Meshing was done using two separate meshing tools, snappyHexMesh and ANSYS Mesher. The snappyHexMesh tool offered the most flexible and effective control over the mesh generation and quality. In order to derive the maximal power output from the Lux VAWT simulations, the Unsteady Reynolds Averaged Navier--Stokes (URANS) equations are solved with different time-stepping methods; the objective is to reduce the computational costs. While attempting to reduce the numerical diffusion from the non-transient terms of URANS, a stabilized trapezoidal rule with a second-order backward differentiation formula (TR--BDF2) time-stepping method was implemented in OpenFOAM. As a result, the transient aerodynamic forces of the blades, the torque, and power output are evaluated. The findings demonstrate that most of the transient aerodynamic force is generated along the axis of rotation of the rotor during one complete revolution. Similarly, the computations indicate that the BDF2 method results in the least computational cost and predicts a turbine power that is somewhat comparable to the experimental results. The difference between the simulation results and the experimental data is attributed partly to the pressure fluctuations on the turbine blades due to the mesh topology

CFD simulations to improve air distribution inside cold climate broiler houses involving heat exchangers

While chicken meat production is less polluting than other meats, it remains a problem, given a target of 1 ton CO2-eq per capita in 2050. Most of the emissions are associated with feed production, but cold climate requires an additional energy input for space heating. This input is usually provided by propane gas. Since 2014, energy efficiency has sparked in the world of broiler production. Heat recuperation through heat exchanger can reduce significantly the heating requirement, by preheating fresh air inlet with stale air outlet. While there have been many studies on the improvement of direct ventilation in both hot and cold climate, little attention has been given to heat exchangers in broiler houses. It is therefore unknown how best to integrate this equipment in a broiler house to provide homogenous housing conditions (air temperature, humidity, contaminants). This thesis studies the integration of heat exchangers (HX) in a commercial broiler house located in a cold climate (Sainte-Mélanie, Canada). The goal is to improve the housing conditions of a rectangular 1760 m3 broiler house equipped with two ductless air-to-air heat exchangers (0.38 m3s-1). Computational fluid dynamics (CFD) software OpenFOAM was used to create a 3D steady-state buoyant simulation with RNG k-ε turbulence model. CFD model was validated with experimental data collected at the participating broiler house. In the original configuration (C0), the two heat exchangers are parallel, on the same longitudinal wall. Three alternative configurations (C1, C2, and C3) were studied to improve housing conditions at chick height (0.1 m): C1 consists of increasing the distance between the HX, C1 consists of a 30° rotation of the HX, and C3 consists of positioning one HX on each end wall. Air velocity, air temperature and age of air were used as performance criteria. All configurations behaved and performed differently. The configuration with the best overall performance was C2. It showed a 45% improvement in age of air distribution and 24% in velocity distribution. Temperature distribution also improved, but it was not reflected in the coefficient of variation

Modeling of directional solidification of multicrystalline silicon in a traveling magnetic field

Melt flow plays an important role in directional solidification of multicrystalline silicon influencing the temperature field and the crystallization interface as well as the transport of impurities. This work investigates the potential of a traveling magnetic field (TMF) for an active control of the melt flow. A system of 3D numerical models was developed and adapted based on open-source software for calculations of Lorentz force, melt flow, and related phenomena. Isothermal and non-isothermal model experiments with a square GaInSn melt were used to validate the numerical models by direct velocity measurements. Several new 3D flow structures of turbulent TMF flows were observed for different melt heights. Further numerical parameter studies carried out for silicon melts showed that already a weak TMF-induced Lorentz force can stir impurities near to the complete mixing limit. Simultaneously, the deformed temperature field leads to an increase of the deflection of crystallization interface, which may exhibit a distinct asymmetry. The numerical results of this work were implemented in a research-scale silicon crystallization furnace. Scaling laws for various phenomena were derived allowing a limited transfer of the results to the industrial scale