Application of a Higher-order Adaptive Method to RANS Test Cases (Invited)

2015 ◽  
Author(s):  
Yixuan Hu ◽  
Carlee Wagner ◽  
Steven Allmaras ◽  
Marshall Galbraith ◽  
David L. Darmofal
Keyword(s):  
Adaptive Method ◽  
Higher Order ◽  
Test Cases

Application of Higher-Order Adaptive Method to Reynolds-Averaged Navier–Stokes Test Cases

AIAA Journal ◽  
2016 ◽  
Vol 54 (9) ◽  
pp. 2626-2644 ◽  
Author(s):  
Yixuan Hu ◽  
Carlee Wagner ◽  
Steven R. Allmaras ◽  
Marshall C. Galbraith ◽  
David L. Darmofal
Keyword(s):  
Adaptive Method ◽  
Higher Order ◽  
Navier Stokes ◽  
Test Cases ◽  
Reynolds Averaged Navier Stokes

Assessment of Enhanced Multi-Dimensional Limiting Process for Multi-Dimensional Flows

2011 ◽  
Author(s):  
Kyu Hong Kim ◽  
Jung Ho Park
Keyword(s):  
Higher Order ◽  
High Order ◽  
Test Cases ◽  
Computational Domain ◽  
Interpolation Scheme ◽  
Local Extrema ◽  
Numerous Test ◽  
High Order Interpolation

In this paper, a new limiting process based on the Multi-dimensional Limiting Process, called enhanced Multi-dimensional Limiting Process is developed and tested with several cases. The enhanced Multi-dimensional Limiting Process, e-MLP has a number of useful features of MLP limiter such as multi-dimensional monotonicity and straightforward extensionality to higher order interpolation. It is applicable to local extrema and prevents excessive damping in a linear discontinuous region through application of appropriate limiting criteria. It is efficient because a limiting function is applied only to a discontinuous region. In addition, it is robust against shock instability due to the strict distinction of the computational domain and the use of regional information in a flux scheme as well as a high order interpolation scheme. The new limiting process was applied to numerous test cases. Through these tests, we could confirm that e-MLP enhances the accuracy and efficiency with both continuous and discontinuous multidimensional flows.

scholarly journals Tension Estimation Method for Cable With Damper Using Natural Frequencies

2021 ◽  
Vol 7 ◽  
Author(s):  
Aiko Furukawa ◽  
Katsuya Hirose ◽  
Ryosuke Kobayashi
Keyword(s):  
Natural Frequencies ◽  
Numerical Models ◽  
Estimation Error ◽  
Estimation Method ◽  
Higher Order ◽  
Bending Stiffness ◽  
Estimation Accuracy ◽  
Test Cases ◽  
Numerical Verification ◽  
Vibration Method

In the maintenance of cable structures, such as cable-stayed bridges and extra-dosed bridges, it is necessary to estimate the tension acting on the cables. The safety of a cable is confirmed by checking whether the tension acting on the cable is within the allowable value. In current Japanese practice, the tension of a cable is estimated using the vibration method or the higher-order vibration method, which considers the natural frequencies of the cable. However, in recent years, the aerodynamic vibration of cables caused by wind has become a problem owing to the recent increase in the cable length and low damping performance of the cable itself. To suppress the aerodynamic vibration of cables, dampers are installed onto the cables. Because the damper changes the cable’s natural frequencies, the vibration method and higher-order vibration method are inappropriate for measuring the tension of a cable with a damper. In this paper, a new tension estimation method for a cable with a damper is proposed. To model a cable with a tensioned Bernoulli-Euler beam, theoretical equations for estimating the natural frequencies were derived. The proposed method inversely estimates the tension and bending stiffness of the cable and damper parameters, simultaneously, from the natural frequencies. The validity of the proposed method was confirmed by conducting numerical simulations and experiments. In the numerical verification, the performance of the proposed method was investigated using 80 numerical models. In the experimental verification, the estimation accuracy of the proposed method was investigated by considering 16 test cases. Thus, it was confirmed that the tension estimation accuracy was high, whereas the bending stiffness and damper parameter estimation accuracy was unsatisfactory. The tension estimation error was within 10% in all experimental cases, and within 5% if two test cases are excluded. The results obtained by the numerical and experimental verifications confirmed the effectiveness of the proposed method in tension estimation.

Hyperbolic Runge–Kutta Method Using Evolutionary Algorithm

2018 ◽  
Vol 13 (10) ◽  
Author(s):  
A. Arun Govind Neelan ◽  
Manoj T. Nair
Keyword(s):  
Evolutionary Algorithm ◽  
Stability Region ◽  
Strong Stability ◽  
Higher Order ◽  
Test Cases ◽  
Runge Kutta Method ◽  
Higher Order Terms ◽  
Runge Kutta ◽  
The Stability ◽  
Classical Optimization

A family of Runge–Kutta (RK) methods designed for better stability is proposed. Authors have optimized the stability of RK method by increasing the stability region by trading some of the higher order terms in the Taylor series. For flow involving shocks, compromising a few higher order terms will not affect convergence rate that is justified with an example. Though this kind of analysis began about three decades ago, most of the papers dealt with classical optimization and ended up in relatively nonoptimal values. Here, authors have overcome that by using evolutionary algorithm (EA), the result is refined using multisection method (MSM). The schemes designed based on this procedure have better stability than the classical RK methods, strong stability RK methods (SSPRK), and low dispersive and dissipative RK methods (LDDRK) of the same number of stages. Authors have tested the schemes on a variety of test cases and found some significant improvement.

Gridless Adaptive Method for Simulating Unsteady Flows with Moving Shocks

2012 ◽  
Vol 271-272 ◽  
pp. 948-952
Author(s):  
Sai Hu Pu
Keyword(s):  
High Resolution ◽  
Numerical Test ◽  
Unsteady Flows ◽  
Adaptive Method ◽  
Test Cases ◽  
Computational Domain ◽  
Local Pressure ◽  
Time Step ◽  
Physical Features ◽  
Cloud Of Points

In this paper, the gridless adaptive method is extended to simulate unsteady flows with moving shocks. In order to capture physical features like moving shocks with local high resolution, a technique of dynamic cloud of points is achieved by adopting clouds refinement and clouds coarsening procedures during the evolution of the unsteady flows. The regions for clouds refinement and clouds coarsening are determined at every time step by an indicator, which is defined as a function of the local pressure gradient. Once the regions of cloud of points to be adjusted are located by the indicator, the clouds refinement is carried out by introducing new points based on the existing structure of cloud of points, and the clouds coarsening procedure is also implemented simultaneously in order to control the size of the points distributed in the whole computational domain. The numerical test cases show that the gridless adaptive method presented can capture moving shocks with high resolution successfully in both inviscid and viscous test cases.

scholarly journals Can AlphaFold2 predict protein-peptide complex structures accurately?

2021 ◽  
Author(s):  
Junsu Ko ◽  
Juyong Lee
Keyword(s):  
Structure Prediction ◽  
Good Accuracy ◽  
Higher Order ◽  
Order Structure ◽  
Sequence Information ◽  
Test Cases ◽  
Complex Structures ◽  
Peptide Complex ◽  
Peptide Complexes

In this preprint, we investigated whether AlphaFold2, AF2, can predict protein-peptide complex structures only with sequence information. We modeled the structures of 203 protein-peptide complexes from the PepBDB DB and 183 from the PepSet. The structures were modeling with concatenated sequences of receptors and peptides via poly-glycine linker. We found that for more than half of the test cases, AF2 predicted the bound structures of peptides with good accuracy, C_alpha-RMSD of a peptide < 3.0 angstrom. For about 40% of cases, the peptide structures were modeled with an accuracy of C_alpha-RMSD < 2.0 angstrom. Our benchmark results clearly show that AF2 has a great potential to be applied to various higher-order structure prediction tasks.

scholarly journals A Few Benchmark Test Cases for Higher-Order Euler Solvers

2017 ◽  
Vol 10 (4) ◽  
pp. 711-736 ◽  
Author(s):  
Liang Pan ◽  
Jiequan Li ◽  
Kun Xu
Keyword(s):  
Density Ratio ◽  
Strong Shock ◽  
Kinetic Scheme ◽  
Higher Order ◽  
Two Dimensions ◽  
Test Cases ◽  
Rarefaction Waves ◽  
Shock Interactions ◽  
Large Density Ratio ◽  
Set Up

AbstractThere have been great efforts on the development of higher-order numerical schemes for compressible Euler equations in recent decades. The traditional test cases proposed thirty years ago mostly target on the strong shock interactions, which may not be adequate enough for evaluating the performance of current higher-order schemes. In order to set up a higher standard for the development of new algorithms, in this paper we present a few benchmark cases with severe and complicated wave structures and interactions, which can be used to clearly distinguish different kinds of higher-order schemes. All tests are selected so that the numerical settings are very simple and any higher order scheme can be straightforwardly applied to these cases. The examples include highly oscillatory solutions and the large density ratio problem in one dimensional case. In two dimensions, the cases include hurricane-like solutions; interactions of planar contact discontinuities with asymptotic large Mach number (the composite of entropy wave and vortex sheets); interaction of planar rarefaction waves with transition from continuous flows to the presence of shocks; and other types of interactions of two-dimensional planar waves. To get good performance on all these cases may push algorithm developer to seek for new methodology in the design of higher-order schemes, and improve the robustness and accuracy of higher-order schemes to a new level of standard. In order to give reference solutions, the fourth-order gas-kinetic scheme (GKS) will be used to all these benchmark cases, even though the GKS solutions may not be very accurate in some cases. The main purpose of this paper is to recommend other CFD researchers to try these cases as well, and promote further development of higher-order schemes.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Linear Visco-Resistive Computations of Magnetohydrodynamic Waves: I. The Code and Test Cases

1994 ◽  
Vol 144 ◽  
pp. 503-505
Author(s):  
R. Erdélyi ◽  
M. Goossens ◽  
S. Poedts
Keyword(s):  
Resonant Absorption ◽  
Numerical Code ◽  
Mhd Waves ◽  
Test Cases ◽  
Numerical Accuracy ◽  
Element Discretization ◽  
Flux Tubes ◽  
Magnetohydrodynamic Waves ◽  
Viscosity Coefficients ◽  
Magnetic Flux Tubes

AbstractThe stationary state of resonant absorption of linear, MHD waves in cylindrical magnetic flux tubes is studied in viscous, compressible MHD with a numerical code using finite element discretization. The full viscosity tensor with the five viscosity coefficients as given by Braginskii is included in the analysis. Our computations reproduce the absorption rates obtained by Lou in scalar viscous MHD and Goossens and Poedts in resistive MHD, which guarantee the numerical accuracy of the tensorial viscous MHD code.

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