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- BoundaryLayer setup for Gmsh 3D meshing
- from gmsh geo file to fenics mesh with subdomain and boundary facet exported
- FreeCAD compatible Fenics mshr geometry building
- solved Fenics (2016.2) cpp code compiling error on ubuntu 16.04
- Cmake cheatsheet
- c and cpp pitfalls, mixing signed and unsigned integer, implicit conversion
- compile c++ codes using Visual C++ Build Tools from the command prompt
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- Evaluation of OpenFOAM on bash on Ubuntu on windows 10
- disable windows input method hotkey
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BoundaryLayer setup for Gmsh 3D meshing
Precise control of the thickness of the first cell normal to wall, is crucial for turbulence models like k-epsilon, k-omega. Before moving to turbulence flow simulation for CFD workbench of FreeCAD 2D meshing with boundary layer, tutorial <http://www.iesensor.com/blog/2017/05/24/gmsh_fenics_meshing/> 3D boundary … Continue reading
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from gmsh geo file to fenics mesh with subdomain and boundary facet exported
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from dolfin import * import os.path from subprocess import Popen, PIPE, check_output # https://fenicsproject.org/qa/9983/setting-boundary-conditions-for-meshes-generated-by-gmsh # generete mesh by: gmsh test.geo -3 # dolfin-convert -i gmsh test.msh test.xml geo_file_content = """ size = 1; //m meshThickness = size / 3; gridsize = size / 5; // All numbering counterclockwise from bottom-left corner Point(1) = {0, 0, 0, gridsize}; Point(2) = {0, size, 0, gridsize}; Point(3) = {size, size, 0, gridsize}; Point(4) = {size, 0, 0, gridsize}; Line(1) = {1, 2}; Line(2) = {2, 3}; Line(3) = {3, 4}; Line(4) = {4, 1}; Line Loop(4) = {1, 2, 3, 4}; Plane Surface(8) = {4}; Physical Line(12) = {1}; Physical Line(23) = {2}; Physical Line(34) = {3}; Physical Line(41) = {4}; Physical Surface(1) = {8}; // do not comment out this line //Transfinite Surface{8}; // fenics does not support recomine //Recombine Surface{8}; // boundary layer Field[4] = BoundaryLayer; Field[4].EdgesList = {1,3}; // FacesList for 3D Field[4].hfar = 10; Field[4].hwall_n = 0.015; Field[4].hwall_t = 0.01; Field[4].thickness = 0.02; Field[4].ratio = 1.0; BoundaryLayer Field = 4; Mesh.CharacteristicLengthFromCurvature = 1; Mesh.Algorithm = 8; // delannay=1 """ fname="test" with open(fname+".geo", 'w') as f: f.write(geo_file_content) cmd = 'gmsh {}.geo -3'.format(fname) print check_output([cmd], shell=True) # run in shell mode in case you are not run in terminal cmd = 'dolfin-convert -i gmsh {}.msh {}.xml'.format(fname, fname) Popen([cmd], stdout=PIPE, shell=True).communicate() mesh = Mesh(fname+".xml") if os.path.exists( fname+"_physical_region.xml"): subdomains = MeshFunction("size_t", mesh, fname+"_physical_region.xml") plot(subdomains) if os.path.exists( fname+"_facet_region.xml"): boundaries = MeshFunction("size_t", mesh, fname+"_facet_region.xml") plot(boundaries) plot(mesh) interactive() |
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FreeCAD compatible Fenics mshr geometry building
Fenics geometry building API is based on CGAL, it can import CAD, but can not export CAD file like step. Here is a solution, not fully tested. This file may be further developed in github.
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solved Fenics (2016.2) cpp code compiling error on ubuntu 16.04
for any expression in Expression for Fenics 2016.2( installed from PPA ) expr = “”” x[2]> {} ? {}:{}”””.format(disc_zmax, lambda_p, lambda_d) print(expr) K = Expression(expr, element=V.ufl_element()) # error in compiling instant error log: ” — The imported target “vtkRenderingPythonTkWidgets” references … Continue reading
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Cmake cheatsheet
#Cmake cheat sheet in markdown
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c and cpp pitfalls, mixing signed and unsigned integer, implicit conversion
1. mixing unsigned and sign int is a bad idea first of all, remember: signed int types will be implicitly converted to unsigned if sizeof(signed int types) == sizeof(unsigned int types) Google C++ coding standard, say “do not use unsigned … Continue reading
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compile c++ codes using Visual C++ Build Tools from the command prompt
Introducing the Visual Studio Build Tools “If you have installed Microsoft Visual C++ Build Tools 2015 on Windows 10, open the Start menu and choose All apps. Scroll down and open the Visual C++ Build Tools folder. Choose Visual C++ … Continue reading
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Mibox 2 install youtube and play to kodi (just as chromecast)
1. install shafa TV manager and/or ES file explorer to be enable install apk from USB/SD card http://www.shafa.com/articles/yWNpNK6erhB6Q4dO.html 2. install Kodi/XMBC apk from shafa’s file manager (in toolbox) on USB storage 3. install apk of youtube for Google TV, and … Continue reading
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Evaluation of OpenFOAM on bash on Ubuntu on windows 10
## installation After Anniversary Build (2016 Aug) for x65 windows 10, it is possible to evaluate this beta feature in developer mode without upgrade to claimed unstable insider version. see detailed tutorial: To install ubuntu on windows 10 from power … Continue reading
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disable windows input method hotkey
UPDATE: it seems the following methods still fails, as restart pc or windows update will invalidated the setting =========== Avoid the annoying hotkey to trigger the IME shape/punctation in Chinese for half/full see tutorial: http://superuser.com/questions/327479/ctrl-space-always-toggles-chinese-ime-windows-7 In addition to disapble Ctrl-Space, … Continue reading
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Toshiba L650 laptop disassembling
I got a 5 year old laptop, it does not boot, no screen show, no beeping. So I need to disassemble and check. Generally, this laptop is easy to repalce harddisk or memory on the back. And the dissabling is … Continue reading
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Introduction to Industrial IO (sensor framework for Linux)
introduciton to Industrial IO overview of industrial IO. In short, SPI and I2C sensor framework for Linux sensor categories: “ADC, DAC, light, accel(erometer), gyro, magnetometer, humidity, temperature, amplifier, frequency, orientation, health”, etc merged to mainline kernel 3.14, used by beagleBone, … Continue reading
A recommendation for free of charge 2D CAD and office system, also cross-platform
for office system, I recommend kingsoft WPS office, which is based on Qt, much faster than java based solution. It has Android, Linux version in alpha, in addition to mature windows ‘s version http://wps-community.org/download.html For 2D CAD drawing, I recommend … Continue reading
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Solve CFD via OpenFOAM in free CAx platform FreeCAD
Updated 2016-04-17 Boundary condition setup GUI has been done for preview This is an early preview, only for people with experience of OpenFoam. Test instruction could be found at https://github.com/qingfengxia/FreeCAD/ … /Readme.md I would love to see some feedback for … Continue reading
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Why power adapters for laptop are NOT compatible
see the word document contains figure to demonstrate various power adapters from diff manufacturers and how the claimed incompatible adapter could be reused. why laptop power adapter are not compatible and howto
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Using paraview to visualise vorticity (Lambda2, vorticity, Q-Criterion)
Please download the word document, which contains the details on setting up the Python Calculator filter to calc lambda2, and use the advanced option of ‘Gradient’ filter to calculate vorticity, Q-Criterion. This code is not tested, some user has already … Continue reading
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What is the max array size you can declare (big data challenge)
by Qingfeng Xia @ iesensor.com 2015 With the popularity of BIG DATA concept, have you think about what is the max data structure you can run?http://stackoverflow.com/questions/216259/is-there-a-max-array-length-limit-in-c
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Ten things you must do after install Openwrt 15.05 on raspberry pi B
This is not a tutorial, but list some interesting things for Openwrt 2015-09-14 by Qingfeng Xia
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Gmail backup to your google drive using app script (isenensor.com)
Link to my google spread sheet with script: Gmail backup isenensor.com https://docs.google.com/spreadsheets/d/1vcQ-dJ_9iEmISLDnDjAFWrb4zcGOhEJzIJmMoq_MLYQ/pubhtml
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Electronics under extreme environment (high temperature, low temperature)
Electronics under extreme environment Collection of public resource, product catalog, NASA presentation, etc
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