doi: JSVIAG 0022-460X Crossref Google Scholar J., “ A Computational Mode-Matching Approach for Sound Propagation in Three-Dimensional Ducts with Flow,” Journal of Sound and Vibration, Vol. 315, Nos. 4–5, Sept. 2008, pp. 1103–1124. and Casalis G., “ Discontinuous Galerkin Method for Acoustic Modes Computation in Lined Ducts,” 18th AIAA/CEAS Aeroacoustics Conference, AIAA Paper 2012-2153, June 2012. M., “ Acoustic Scattering by a Spliced Turbofan Inlet Duct Liner at Supersonic Fan Speeds,” Journal of Sound and Vibration, Vol. 292, Nos. 3–5, 2006, pp. 911–934. and Eversman W., “ Transmission in Flow Ducts with Peripherally Varying Liner,” 6th AIAA Aeroacoustics Conference, AIAA Paper 1980-1015, June 1980. Watson W., “ Noise Suppression Characteristics of Peripherally Segmented Duct Liners,” NASA TP-1904, 1981. An approximate method is also described to account for the effect of the nonlinear propagation on linear predictions of the liner performance when repairs are present. A close agreement is demonstrated with results from an asymptotic analytical model valid for small patch widths. The effects of the extent and the location of a hard patch, representing the liner damage and repair, on the overall performance of the liner are predicted. In the current paper, the acoustic effect of damage and repair in a zero-splice liner is simulated numerically. However, damage can occur to such liners in service, and the extent to which local liner repairs reduce the effectiveness of the zero-splice design then becomes an issue. The significance of this “splice effect” has led to the adoption of “zero-splice” liners in recent turbofan nacelles. The splices scatter energy from strong rotor-locked tones into adjacent azimuthal orders for which the liner is less effective, thereby degrading the liner performance. Field.Traditional installations of turbofan intake liners include acoustically “hard” axial splices between liner segments for ease of fabrication and assembly. not forget to write : Background Field = 1 geo file for people who would encounter the same difficulties as me : When reopening the panel, it remains set on nglib. I clicked on the elmergrid option, applied but In Mesh>configure I saw that the preferred generator is set on nglibĪnd not elmergrid. Now I opened it in Elmer GUI, File>open, the design is completly destroyed, (I found out how to create it ), it opens well in Gmsh. This time ElmerGrid ran, I got the file with a beautiful boundary layer I didn't find how to create a boundary layer on the gmesh website, I am going to search more. I entered values for the boundary layer, Apply,Īnd it created my mesh but not the boundary layer. Then Mesh>Define>Size field>Boundary layer. In fact I have created points (with z=0), then lines on points, then an area on the lines, Your command must be good, but after opening ElmerGrid in a Terminal, typing ElmerGrid 14 2 ancre3 -autoclean I installed FreeCAD (on the File tab of the top boarder, only the Quit option appears, the software seems not to be finished) and LibreCAD (saves files in. I installed Grace for modeler but inside Grace I didn't find the possible extensions for saved files. But by loading into Netgen, an error message appears : « geo-file should start with algebraic 3D ». in2d files for 2D geometries, so I tried to load the. The geometry file could not be open in Elmer as well (a message appears, saying « Unable to mesh, no input data or mesh generator (please make sure that your input file suffix is in lower case) ». But no one of the meshed files could be loaded in Elmer. I installed Gmesh, which has a modeler, I draw my geometry, saved in. I installed then Netgen, but I didn't find any modeler inside, as it seems to be only a mesher. I tried then to create the geometry with Elmer modeler but on the Elmer modeler window no command appear but Editor with 2 tabs (one is Points with Idx, x, y, the other is Curve with out, in, pts, p1, p2, p3), and nothing happens by picking with the mouse. I have installed Elmer on my Ubuntu 12.04 configuration. I need to study a turbulent flow around a beam in 2D. I don't know which software to use to create a 2D geometry file or a meshed file that could be loaded to Elmer.
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