A ray tracing engine integrated with Blender and with uncertainty estimation: Description and initial results

2020 ◽  
pp. 1351010X2096475
Author(s):  
Eric Brandão ◽  
Gonçalo Morgado ◽  
William D’A Fonseca
Keyword(s):  
Ray Tracing ◽  
Computational Cost ◽  
Sound Intensity ◽  
Measured Data ◽  
Absorption Data ◽  
Uncertainty Prediction ◽  
Research And Teaching ◽  
Software Packages ◽  
Separate Step ◽  
Good Agreement

This paper presents a ray tracing algorithm developed as a research and teaching tool. The motivations to pursue this task and some novel features of the algorithm are presented. Amongst them, it is possible to cite: (i) the receivers may grow in size, which saves some computational cost; (ii) sound intensity calculations are performed in a separate step than geometrical ray tracing; and (iii) those features allow Monte Carlo simulations for uncertainty prediction related to absorption data. The results obtained with the proposed algorithm are compared with the measured data (and other software packages) of Round Robins II (Elmia Hall) and III (PTB recording studio) and proved to be in good agreement with measured data. The ratio of the mean error by the JND of each parameter are compatible with the results presented by the other round robin participants. The product of this research is also scalable to an hybrid algorithm and alternatives to do so are provided through the discussion in the paper.

Use of a three-dimensional model to predict heavy metal (copper) fluxes in the Oujiang estuary

2014 ◽  
Vol 69 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
Shasha Lu ◽  
Ruijie Li ◽  
Xiaoming Xia ◽  
Jun Zheng
Keyword(s):  
River Discharge ◽  
Water Surface ◽  
Three Dimensional ◽  
Measured Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Pollutant Concentrations ◽  
Suspended Sediment Concentrations ◽  
Adsorption Desorption ◽  
Good Agreement

Measuring pollutant concentrations in major tributaries is the standard method for establishing pollutant fluxes to the sea. However, this method is costly and difficult, and may be subject to a great deal of uncertainty due to the presence of unknown sources. This uncertainty presents challenges to managers and scientists in reducing contaminant discharges to water bodies. As one less costly method, a three-dimensional model was developed and used to predict pollutant fluxes to the sea. The sorptive contaminant model was incorporated into hydrodynamic and sediment models. Adsorption–desorption of copper by sediments in the Oujiang estuary were described using Henry's law. The model was validated using measured data for water surface elevations, flow velocity/direction, suspended sediment concentrations, and the proportion of copper sorbed to sediment. The validated model was then applied to predict fluxes of copper. Combined with the measured data, the copper concentration in the Oujiang River discharge was calculated as 13.0 μg/L and copper fluxes were calculated as 52 t in 2010. This copper flux prediction was verified using measured dissolved copper concentrations. Comparisons between the modeled and measured results showed good agreement at most stations, demonstrating that copper flux prediction in the Oujiang estuary was reasonably accurate.

Analysis of Transonic Bladerows With Non-Uniform Geometry Using Spectral Method

2020 ◽  
Author(s):  
Feng Wang ◽  
Luca di Mare
Keyword(s):  
Flow Field ◽  
Spectral Method ◽  
Computational Cost ◽  
Leading Edge ◽  
Wave Number ◽  
Efficient Tool ◽  
Flow Solver ◽  
Engine Order ◽  
Harmonic Flow ◽  
Good Agreement

Abstract Turbomachinery blade rows can have non-uniform geometries due to design intent, manufacture errors or wear. When predictions are sought for the effect of such non-uniformities, it is generally the case that whole assembly calculations are needed. A spectral method is used in this paper to approximate the flow fields of the whole assembly but with significantly less computation cost. The method projects the flow perturbations due to the geometry non-uniformity in an assembly in Fourier space, and only one passage is required to compute the flow perturbations corresponding to a certain wave-number of geometry variation. The performance of this method on transonic blade rows is demonstrated on a modern fan assembly. Low engine order and high engine order geometry non-uniformity (e.g. “saw-tooth” pattern) are examined. The non-linear coupling between the flow perturbations and the passage-averaged flow field is also demonstrated. Pressure variations on the blade surface and the potential flow field upstream of the leading edge from the proposed spectral method and the direct whole assembly solutions are compared. Good agreement is observed on both quasi-3D and full 3D cases. A lumped approach to compute deterministic fluxes is also proposed to further reduce the computational cost of the spectral method. The spectral method is formulated in such a way that it can be easily implemented into an existing harmonic flow solver by adding an extra source term, and can be potentially used as an efficient tool for aeromechanical and aeroacoustics design of turbomachinery blade rows.

scholarly journals Discharge and Sediment Transport in a River Basin. Assessment Before and After the Construction of a Dam at the Upper Basin Boundary

2021 ◽  
Author(s):  
George Paschalidis ◽  
Ilias IIordanidis ◽  
Petros Anagnostopoulos
Keyword(s):  
Sediment Transport ◽  
Meteorological Data ◽  
Climatic Data ◽  
Northern Greece ◽  
Basin Boundary ◽  
Software Packages ◽  
Before And After ◽  
The Mean ◽  
Gis Interface ◽  
Good Agreement

Abstract The purpose of this study is the evaluation of runoff and sediment transport in the basin of the Nestos River (Northern Greece) downstream of the dam of Platanovrisi, constructed in 1998. The model used for the simulation was AGNPS, which is based on the Revised Universal Soil Loss Equation (RUSLE), combined with a GIS interface. Two different simulations were conducted, one for the years 1980-1990 and another for the period 2006-2030, before and after the construction of the dam respectively. For the simulation for the period 1980-1990 existing meteorological data were employed, and the results were in good agreement with those of a different study (Hrissanthou, 2002). The simulation for the period 2006-2030 was based on rainfall and climatic data generated from the software packages GlimClim and ClimGen. The mean runoff was by 5% lower and the mean annual sediment yield by 20% lower than the corresponding values for the period 1980-1990.

ANALYSIS OF TRANSONIC BLADEROWS WITH NON-UNIFORM GEOMETRY USING SPECTRAL METHOD

2021 ◽  
pp. 1-27
Author(s):  
Feng Wang ◽  
Luca di Mare
Keyword(s):  
Flow Field ◽  
Spectral Method ◽  
Computational Cost ◽  
Leading Edge ◽  
Wave Number ◽  
Efficient Tool ◽  
Flow Solver ◽  
Engine Order ◽  
Harmonic Flow ◽  
Good Agreement

Abstract Turbomachinery blade rows can have non-uniform geometries due to design intent, manufacture errors or wear. When predictions are sought for the effect of such non-uniformities, it is generally the case that whole assembly calculations are needed. A spectral method is used in this paper to approximate the flow fields of the whole assembly but with significantly less computation cost. The method projects the flow perturbations due to the geometry non-uniformity in an assembly in Fourier space. Only one passage is required to compute the flow perturbations corresponding to a certain wave-number of geometry variation. The performance of this method on transonic blade rows is demonstrated on a modern fan assembly. Low and high engine order geometry non-uniformity (e.g. “saw-tooth” pattern) are examined. The non-linear coupling between the flow perturbations and the passage-averaged flow field is also demonstrated. Pressure variations on the blade surface and the potential flow field upstream of the leading edge from the proposed method and the direct whole assembly solutions are compared. Good agreement is observed on both quasi-3D and full 3D cases. A lumped approach to compute deterministic fluxes is also proposed to further reduce the computational cost of the spectral method. The spectral method is formulated in such a way that it can be easily implemented into an existing harmonic flow solver by adding an extra source term, and can be used as an efficient tool for aeromechanical and aeroacoustics design of turbomachinery blade rows.

scholarly journals ∆E/∆E Measurements of Energetic Ions Using CVD Diamond Detectors

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Ahmed Alghamdi ◽  
Lawrence Heilbronn ◽  
Luis A. Castellanos ◽  
Eric Lukosi
Keyword(s):  
Detection System ◽  
National Laboratory ◽  
Cvd Diamond ◽  
Brookhaven National Laboratory ◽  
Measured Data ◽  
Geant4 Simulation ◽  
Computational Results ◽  
Energetic Ions ◽  
Radiation Laboratory ◽  
Good Agreement

Experimental and computational results of a ΔE/ΔE diamond detection system are presented. The ΔE/ΔE detection system was evaluated using energetic proton and iron beams striking thick polyethylene targets at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). The measured data for diamond sensor A show good agreement with the Geant4 simulation. In addition, simulations have demonstrated the ability to identify hydrogen isotopes using a diamond detection system.

scholarly journals Numerical and experimental investigation on the thermal behaviour of the building integrating occupant thermal comfort

2020 ◽  
Vol 307 ◽  
pp. 01025 ◽  
Author(s):  
Abed Al Waheed Hawila ◽  
Abdelatif Merabtine ◽  
Nadège Troussier
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Thermal Behaviour ◽  
Room Temperature ◽  
Maximum Error ◽  
Measured Data ◽  
Influential Factor ◽  
Simulation Tools ◽  
Good Agreement

Simulation tools are widely used to model buildings in order to predict their indoor air quality and energy consumption. The prediction capability of the model is an influential factor in determining the ability of the building to be energy efficient and thermally comfortable. Thus, the validation of the developed models is crucial. In this context, this paper presents a numerical model developed using an object-oriented modelling tool based on the Modelica approach and a case study validation of this model. Then the thermal behaviour of the building and the occupants’ thermal comfort in the considered case study are investigated. The objective is to validate the developed model firstly by comparing predicted results with measured data regarding room temperature and relative humidity, and secondly by comparing the calculated thermal comfort indices (PMV and PPD) based on predicted results and measured data. The results show good agreement between simulations and experiments, with a maximum error in room temperature and relative humidity of 1.7 °C and 4.5%, respectively, and only 1% and 1.5% difference between averaged values of PMV and PPD, respectively.

scholarly journals CONTRIBUTIONS TO THE MARINE PROPELLERS HYDRODYNAMIC DESIGN

2014 ◽  
Vol 13 (2) ◽  
pp. 41
Author(s):  
B. I. Favacho ◽  
J. R. P. Vaz ◽  
A. L. A. Mesquita
Keyword(s):  
Control Volume ◽  
Computational Cost ◽  
Momentum Balance ◽  
Marine Propellers ◽  
Energy And Momentum ◽  
Thrust And Torque ◽  
The Mathematical Model ◽  
Low Computational Cost ◽  
Bem Theory ◽  
Good Agreement

The navigation in Amazon region is very important due to the length of navigable rivers and the lack of alternative road network, as well as being a form of transportation costless for the flow of agricultural and manufacturing production. This kind of transportation present social, economic and technological importance for this region. Thus, this work objective to develop a mathematical approach for the marine propellers design, using a formulation for chord and pitch angle optimization, taken into account the equations of mass, energy and momentum balance for the theoretical calculation of thrust and torque relationships on an annular control volume, ie, the mathematical model is based in the Blade Element Momentum (BEM) theory. The proposed hydrodynamic model present low computational cost and it is easy to implement. The results are compared with classical Glauert's theory and the experimental data of the Wageningen B3-50 propeller, presenting good agreement.

The breaking of transient inertio-gravity waves in a shear flow using the Gaussian beam approximation

2014 ◽  
Vol 759 ◽  
pp. 676-700 ◽  
Author(s):  
C. Rodas ◽  
M. Pulido
Keyword(s):  
Shear Flow ◽  
Gaussian Beam ◽  
Ray Tracing ◽  
Gravity Waves ◽  
Convective Instability ◽  
Shear Flows ◽  
Computational Cost ◽  
Dynamical Instability ◽  
Initial Time ◽  
Instability Criterion

AbstractThe propagation of transient inertio-gravity waves in a shear flow is examined using the Gaussian beam formulation. This formulation assumes Gaussian wavepackets in the spectral space and uses a second-order Taylor expansion of the phase of the wave field. In this sense, the Gaussian beam formulation is also an asymptotic approximation like spatial ray tracing; however, the first one is free of the singularities found in spatial ray tracing at caustics. Therefore, the Gaussian beam formulation permits the examination of the evolution of transient inertio-gravity wavepackets from the initial time up to the destabilization of the flow close to the critical levels. We show that the transience favours the development of the dynamical instability relative to the convective instability. In particular, there is a well-defined threshold for which small initial amplitude transient inertio-gravity waves never reach the convective instability criterion. This threshold does not exist for steady-state inertio-gravity waves for which the wave amplitude increases indefinitely towards the critical level. The Gaussian beam formulation is shown to be a powerful tool to treat analytically several aspects of inertio-gravity waves in simple shear flows. In more realistic shear flows, its numerical implementation is readily available and the required numerical calculations have a low computational cost.

Analysis of Buckling of Sandwich Plates with Viscoelastic Core Using Layerwise Theory

2015 ◽  
Vol 798 ◽  
pp. 462-469 ◽  
Author(s):  
Arash Ranjbaran ◽  
Mohammad Reza Khoshravan ◽  
Mahsa Kharazi
Keyword(s):  
Composite Laminates ◽  
Ritz Method ◽  
Computational Cost ◽  
Shear Deformation Theory ◽  
Element Model ◽  
Sandwich Plates ◽  
Layerwise Theory ◽  
Buckling Behavior ◽  
Viscoelastic Core ◽  
Good Agreement

Sandwich plates are one of the important components in construction of engineering and especially aerospace structures. In this paper, buckling analysis of sandwich plates was investigated experimentally and analytically using layerwise theory. The sandwich plate was rectangular and made of two composite laminates as skins and a viscoelastic core. The formulation was based on the first order shear deformation theory and the Rayleigh-Ritz method was used for approximating and determining the displacement field. The behavior of viscoelastic material modeled using Zener three-element model. The results obtained from layerwise theory compared with experimental results and showed good agreement. This study demonstrated that, layerwise theory could describe buckling behavior of sandwich plates with high accuracy and represents more realistic and acceptable description of behavior of the plates with much less computational cost.

On Blade Damping Technology Using Passive Piezoelectric Dampers

2012 ◽  
Author(s):  
Sebastian M. Schwarzendahl ◽  
Jaroslaw Szwedowicz ◽  
Marcus Neubauer ◽  
Lars Panning ◽  
Jörg Wallaschek
Keyword(s):  
Mode Shape ◽  
Mechanical Strain ◽  
Piezoelectric Element ◽  
Measured Data ◽  
Experimental Investigations ◽  
Response Functions ◽  
Ambient Conditions ◽  
Optimal Position ◽  
Measured Frequency Response ◽  
Good Agreement

This paper deals with a new damping concept for turbine blade vibrations utilizing piezoelectric material. A passive piezo damper consists of a piezoelectric element and a passive electric network connected to its electrodes. The damping performance depends on the size and location of the piezoelectric element with respect to the mode shape of the mechanical strain. Numerical and experimental investigations are carried out on a rigidly clamped simplified compressor blade at stand still and ambient conditions. An optimization process incorporating electromechanical finite element calculations determines the optimal position of the piezo damper in regard to the mode shape of interest. By applying the computed and measured Frequency Response Functions, the damping performance with and without piezo-damper are compared and referred to the measured material damping. The obtained numerical results are in very good agreement with the measured data, leading to a promising damping performance in real application.

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