Euler correction method for two- and three-dimensional transonic flows

AIAA Journal ◽  
1989 ◽  
Vol 27 (10) ◽  
pp. 1377-1386 ◽  
Author(s):  
Thong Q. Dang ◽  
Lee-Tzong Chen
Keyword(s):  
Three Dimensional ◽  
Correction Method ◽  
Transonic Flows

A Correction Method for Non-Vertical View Angle Three-Dimensional Display

2014 ◽  
Vol 513-517 ◽  
pp. 3882-3885
Author(s):  
Tian Qi Zhao ◽  
Xun Bo Yu ◽  
Xin Zhu Sang ◽  
Chong Xiu Yu ◽  
Da Xiong Xu ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Three Dimensional ◽  
Correction Method ◽  
Display System ◽  
Video Images ◽  
Three Dimensional Display

An non-vertical stereoscopic 3-D display method by changing the parallax value of the parallax images is proposed. This method is capable of displaying virtual reality with high-immersion sense because the observing depth only depends on the parallax value. An experimental 3-D display system capable of producing high-immersion and virtual reality video images at 45 degree is developed. Furthermore, the effectiveness of the method is demonstrated by using this system.

scholarly journals Comparative Study of the Trueness of the Inner Surface of Crowns Fabricated from Three Types of Lithium Disilicate Blocks

2019 ◽  
Vol 9 (9) ◽  
pp. 1798 ◽  
Author(s):  
Son ◽  
Yu ◽  
Yoon ◽  
Lee
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Lithium Disilicate ◽  
Correction Method ◽  
3D Analysis ◽  
Angular Region ◽  
Second Molar ◽  
Significant Difference ◽  
Inner Surface ◽  
Aided Design

This study set out to compare the three-dimensional (3D) trueness of crowns produced from three types of lithium disilicate blocks. The working model was digitized, and single crowns (maxillary left second molar) were designed using computer-aided design (CAD) software. To produce a crown design model (CDM), a crown design file was extracted from the CAD software. In addition, using the CDM file and a milling machine (N = 20), three types of lithium disilicate blocks (e.max CAD, HASS Rosetta, and VITA Suprinity) were processed. To produce a crown scan model (CSM), the inner surface of each fabricated crown was digitized using a touch-probe scanner. In addition, using 3D inspection software, the CDM was partitioned (into marginal, axis, angular, and occlusal regions), the CDM and CSM were overlapped, and a 3D analysis was conducted. A Kruskal–Wallis test (α = 0.05) was conducted with all-segmented teeth with the root mean square (RMS), and they were analyzed using the Mann–Whitney U-test and the Bonferroni correction method as a post hoc test. There was a significant difference in the trueness of the crowns according to the type of lithium disilicate block (p < 0.001). The overall RMS value was at a maximum for e.max (42.9 ± 4.4 µm), followed by HASS (30.1 ± 9.0 µm) and then VITA (27.3 ± 7.9 µm). However, there was no significant difference between HASS and VITA (p = 0.541). There were significant differences in all regions inside the crown (p < 0.001). There was a significantly high trueness in the angular region inside the crown (p < 0.001). A correction could thus be applied in the CAD process, considering the differences in the trueness by the type of lithium disilicate block. In addition, to attain a crown with an excellent fit, it is necessary to provide a larger setting space for the angular region during the CAD process.

A Double-Passage Shape Correction Method for Predictions of Unsteady Flow and Aeroelasticity in Turbomachinery

2017 ◽  
Vol 9 (4) ◽  
pp. 839-860 ◽  
Author(s):  
Tongqing Guo ◽  
Di Zhou ◽  
Zhiliang Lu
Keyword(s):  
Unsteady Flow ◽  
Turbulent Flows ◽  
Fourier Coefficients ◽  
Three Dimensional ◽  
Correction Method ◽  
Solution Stability ◽  
Shape Correction ◽  
Flow Variables ◽  
Transonic Fan ◽  
Solution Accuracy

AbstractIn this paper, a double-passage shape correction (DPSC) method is presented for simulation of unsteady flows around vibrating blades and aeroelastic prediction. Based on the idea of phase-lagged boundary conditions, the shape correction method was proposed aimed at efficiently dealing with unsteady flow problems in turbomachinery. However, the original single-passage shape correction (SPSC) may show the disadvantage of slow convergence of unsteady solutions and even produce nonphysical oscillation. The reason is found to be related with the disturbances on the circumferential boundaries that can not be damped by numerical schemes. To overcome these difficulties, the DPSC method is adopted here, in which the Fourier coefficients are computed from flow variables at implicit boundaries instead of circumferential boundaries in the SPSC method. This treatment actually reduces the interaction between the calculation of Fourier coefficients and the update of flow variables. Therefore a faster convergence speed could be achieved and also the solution stability is improved. The present method is developed to be suitable for viscous and turbulent flows. And for real three-dimensional (3D) problems, the rotating effects are also considered. For validation, a 2D oscillating turbine cascade, a 3D oscillating flat plate cascade and a 3D practical transonic fan rotor are investigated. Comparisons with experimental data or other solutions and relevant discussions are presented in detail. Numerical results show that the solution accuracy of DPSC method is favorable and at least comparable to the SPSC method. However, fewer iteration cycles are needed to get a converged and stable unsteady solution, which greatly improves the computational efficiency.

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