# Latest

**URL:** https://discourse.channelflow.ch/latest.md

[Latest](https://discourse.channelflow.ch/latest.md) · [Categories](https://discourse.channelflow.ch/categories.md)

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## [Channelflow 2.0 is here!](https://discourse.channelflow.ch/t/channelflow-2-0-is-here/22)

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**Author:** [@tobias.schneider](https://discourse.channelflow.ch/u/tobias.schneider)\
**Replies:** 0\
**Last updated:** [September 7, 2018, 5:00pm UTC](https://discourse.channelflow.ch/t/channelflow-2-0-is-here/22 "2018-09-07T17:00:00Z")

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After several years of development we are releasing Channelflow 2.0! Please try it out! Question, bugs and other issues Questions, installation issues & getting started: For all questions related to the compilation,…

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## [Welcome to Channelflow-2.0 Discourse](https://discourse.channelflow.ch/t/welcome-to-channelflow-2-0-discourse/8)

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**Author:** [@system](https://discourse.channelflow.ch/u/system)\
**Replies:** 0\
**Last updated:** [August 13, 2018, 2:04pm UTC](https://discourse.channelflow.ch/t/welcome-to-channelflow-2-0-discourse/8 "2018-08-13T14:04:41Z")

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channelflow-2.0 is a software system for numerical simulation and dynamical-systems analysis of the Navier-Stokes equations in channel geometries. Channelflow’s Discourse site supports discussions about installation, usa…

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## [Plane Poiseuille flow](https://discourse.channelflow.ch/t/plane-poiseuille-flow/193)

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**Author:** [@crc150](https://discourse.channelflow.ch/u/crc150)\
**Replies:** 1\
**Last updated:** [January 20, 2026, 12:26am UTC](https://discourse.channelflow.ch/t/plane-poiseuille-flow/193 "2026-01-20T00:26:25Z")

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Hello, I am currently trying to run pressure driven (-dPds) Poiseuille flows, in the installation, it says : The following example simulates a pressure driven (-dPds) Poiseuille flow (-Uwall 0) at the Reynolds number 10…

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## [Free-slip boundary condition](https://discourse.channelflow.ch/t/free-slip-boundary-condition/190)

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**Author:** [@duc.nguyen](https://discourse.channelflow.ch/u/duc.nguyen)\
**Replies:** 0\
**Last updated:** [January 10, 2025, 4:00am UTC](https://discourse.channelflow.ch/t/free-slip-boundary-condition/190 "2025-01-10T04:00:39Z")

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Dear all, I am interested in the free-slip boundary condition at walls. So there is any way to do this B.C. in Channelflow? Thanks a lot! Duc

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## [Cannot build shared library into /user/local](https://discourse.channelflow.ch/t/cannot-build-shared-library-into-user-local/189)

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**Author:** [@duc.nguyen](https://discourse.channelflow.ch/u/duc.nguyen)\
**Replies:** 0\
**Last updated:** [October 2, 2024, 2:10am UTC](https://discourse.channelflow.ch/t/cannot-build-shared-library-into-user-local/189 "2024-10-02T02:10:46Z")

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Hi all, I’m a newbie here. I successfully installed Channelflow 2.0, and passed all tests. When I built it as shared library, I used ‘sudo make install’ “mkdir build cd build cmake …/channelflow -DCMAKE\_CXX\_COMPILER=…

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## [Installing on ubuntu22](https://discourse.channelflow.ch/t/installing-on-ubuntu22/180)

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**Author:** [@Michael](https://discourse.channelflow.ch/u/Michael)\
**Replies:** 1\
**Last updated:** [March 26, 2024, 3:26pm UTC](https://discourse.channelflow.ch/t/installing-on-ubuntu22/180 "2024-03-26T15:26:51Z")

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Hi All, Perhaps someone can share how to successfully install channeflow on Ubuntu22? Installing all the default packages and using the cmake command below cmake /home/user/Tools/channelflow/source -DCMAKE\_BUILD\_TYPE=…

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## [Citing channelflow](https://discourse.channelflow.ch/t/citing-channelflow/43)

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**Author:** [@jlangham](https://discourse.channelflow.ch/u/jlangham)\
**Replies:** 5\
**Last updated:** [November 25, 2022, 3:15am UTC](https://discourse.channelflow.ch/t/citing-channelflow/43 "2022-11-25T03:15:38Z")

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Hi guys, Do you have any guidelines for citing Channelflow 2.0? Best, -Jake

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## [Make fail: recompile with -fpic](https://discourse.channelflow.ch/t/make-fail-recompile-with-fpic/86)

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**Author:** [@Sjter](https://discourse.channelflow.ch/u/Sjter)\
**Replies:** 3\
**Last updated:** [November 18, 2022, 10:10pm UTC](https://discourse.channelflow.ch/t/make-fail-recompile-with-fpic/86 "2022-11-18T22:10:42Z")

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Hi, I am having difficulties installing channelflow. I’ve used the cmake command to build the makefile and instalation files, however when i run make -j it returns an error related to linking static and dynamic libraries…

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## [Analytical perturbation with MPI](https://discourse.channelflow.ch/t/analytical-perturbation-with-mpi/174)

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**Author:** [@Michael](https://discourse.channelflow.ch/u/Michael)\
**Replies:** 1\
**Last updated:** [June 27, 2022, 5:53pm UTC](https://discourse.channelflow.ch/t/analytical-perturbation-with-mpi/174 "2022-06-27T17:53:36Z")

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Hello, I’m trying to run the code with an analytical initial condition using the following: FlowField u1=FlowField(Nx, Ny, Nz, 3, Lx, Lz, a, b); u1.makePhysical(); for (int ny=0; ny\<Ny; ++ny) for (int nz=0; nz\<Nz; +…

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## [Channelflow Pressure Boundary Conditions](https://discourse.channelflow.ch/t/channelflow-pressure-boundary-conditions/172)

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**Author:** [@bobuhito](https://discourse.channelflow.ch/u/bobuhito)\
**Replies:** 0\
**Last updated:** [June 7, 2022, 4:06am UTC](https://discourse.channelflow.ch/t/channelflow-pressure-boundary-conditions/172 "2022-06-07T04:06:24Z")

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Can Channelflow easily switch to a Neumann boundary condition for wall pressure? The Dirichlet boundary condition currently imposed keeps the pressure during a Couette flow at zero on the wall and causes the pressure to…

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## [Fatal error: fftw3.h: No such file or directory](https://discourse.channelflow.ch/t/fatal-error-fftw3-h-no-such-file-or-directory/165)

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**Author:** [@chihin](https://discourse.channelflow.ch/u/chihin)\
**Replies:** 0\
**Last updated:** [April 13, 2022, 6:55pm UTC](https://discourse.channelflow.ch/t/fatal-error-fftw3-h-no-such-file-or-directory/165 "2022-04-13T18:55:04Z")

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Hi all, I’m having trouble installing channelflow. I’ve run cmake succesfully, cmake log in the last section. However, I get the following error when I run make install -j 8 fatal error: fftw3.h: No such file or direct…

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## [Question about dot product](https://discourse.channelflow.ch/t/question-about-dot-product/131)

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**Author:** [@Sebastien](https://discourse.channelflow.ch/u/Sebastien)\
**Replies:** 1\
**Last updated:** [December 21, 2021, 9:43am UTC](https://discourse.channelflow.ch/t/question-about-dot-product/131 "2021-12-21T09:43:35Z")

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Dear channelflow developers, I have a question concerning the function dot() in diffops.cpp I have troubles understanding the computation of fdotg when f.Nd= 3 and g.Nd = 9. fdotg(nx, ny, nz, 0) += f(nx, ny, nz, i) \*…

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## [Error adding symbols: DSO missing from command line](https://discourse.channelflow.ch/t/error-adding-symbols-dso-missing-from-command-line/130)

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**Author:** [@ritab](https://discourse.channelflow.ch/u/ritab)\
**Replies:** 2\
**Last updated:** [December 3, 2021, 8:22pm UTC](https://discourse.channelflow.ch/t/error-adding-symbols-dso-missing-from-command-line/130 "2021-12-03T20:22:03Z")

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Hi, I need help with installation. I get the following error during the “make” stage. I have tried to link the libm library with -DCMAKE\_C\_FLAGS but can’t make it go past the following stage. \[ 35%\] Built target chflow …

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## [Parallelization of the example scripts](https://discourse.channelflow.ch/t/parallelization-of-the-example-scripts/122)

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**Author:** [@fiddlerkrt](https://discourse.channelflow.ch/u/fiddlerkrt)\
**Replies:** 4\
**Last updated:** [August 9, 2021, 2:57pm UTC](https://discourse.channelflow.ch/t/parallelization-of-the-example-scripts/122 "2021-08-09T14:57:30Z")

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Hi all, Apologies for my ignorance, but I’d like to run the couette flow example you have provided on multiple processors but I’m not sure how to go about running the code in parallel rather than in serial. Could you pl…

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## [Using multiple processes](https://discourse.channelflow.ch/t/using-multiple-processes/111)

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**Author:** [@mjchan](https://discourse.channelflow.ch/u/mjchan)\
**Replies:** 2\
**Last updated:** [March 4, 2021, 8:28pm UTC](https://discourse.channelflow.ch/t/using-multiple-processes/111 "2021-03-04T20:28:52Z")

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So I installed Channelflow 2.0 on my Manjaro Linux machine, with -DUSEMPI=on. I have openMPI on this machine. Channelflow installed successfully and passed all make tests, but when I attempt to set -np0 and -np1 to anyt…

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## [FlowField class memory management](https://discourse.channelflow.ch/t/flowfield-class-memory-management/107)

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**Author:** [@PratikAghor](https://discourse.channelflow.ch/u/PratikAghor)\
**Replies:** 1\
**Last updated:** [March 4, 2021, 6:26pm UTC](https://discourse.channelflow.ch/t/flowfield-class-memory-management/107 "2021-03-04T18:26:59Z")

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Hi all, I was doing a computation which involved calling a series of FlowFields in a loop and the minimal code was something as follows: for (Real ta = 0; ta \<= T; ta += n \* dt) { for (Real tb = 0; tb \<= T; t…

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## [Issues with MacOS install, Request: Updated Document for MacOS install](https://discourse.channelflow.ch/t/issues-with-macos-install-request-updated-document-for-macos-install/110)

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**Author:** [@mjchan](https://discourse.channelflow.ch/u/mjchan)\
**Replies:** 0\
**Last updated:** [February 5, 2021, 1:46am UTC](https://discourse.channelflow.ch/t/issues-with-macos-install-request-updated-document-for-macos-install/110 "2021-02-05T01:46:30Z")

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Hi, I was wondering If it might be possible for the Mac OS X installation document here to be updated? I have reached the section titled “Prepare channelflow for installation,” at which point the text files and directory…

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## [Fourier Coefficients in y](https://discourse.channelflow.ch/t/fourier-coefficients-in-y/98)

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**Author:** [@chihin](https://discourse.channelflow.ch/u/chihin)\
**Replies:** 3\
**Last updated:** [June 12, 2020, 7:36am UTC](https://discourse.channelflow.ch/t/fourier-coefficients-in-y/98 "2020-06-12T07:36:59Z")

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Hi all, I am new to both c++ and channelflow so I would advice some patience. I am trying to extract the fourier coefficients in both x and z direction ( \\hat u(kx,y,kz) ) which are function of y. On channelflow 1.0, I…

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## [Understanding the Grid resolution](https://discourse.channelflow.ch/t/understanding-the-grid-resolution/103)

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**Author:** [@gaw](https://discourse.channelflow.ch/u/gaw)\
**Replies:** 0\
**Last updated:** [June 11, 2020, 3:42am UTC](https://discourse.channelflow.ch/t/understanding-the-grid-resolution/103 "2020-06-11T03:42:05Z")

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I have run the code and looked at some results. One thing I found puzzling was the spectra. For example if I set Nz to 48 I would expect 24 non zero values in the spectra. Instead I find 16 which tells me this is probab…

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## [Make test fails](https://discourse.channelflow.ch/t/make-test-fails/91)

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**Author:** [@chihin](https://discourse.channelflow.ch/u/chihin)\
**Replies:** 6\
**Last updated:** [June 4, 2020, 9:43am UTC](https://discourse.channelflow.ch/t/make-test-fails/91 "2020-06-04T09:43:09Z")

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Hi all, I’m new to channelflow and I am using it for my Master’s Thesis. I’ve been trying to install channelflow and have been encountering some difficulties as I can’t get all the subroutines to pass when make test is…

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## [Odd results with benchmark times](https://discourse.channelflow.ch/t/odd-results-with-benchmark-times/97)

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**Author:** [@gaw](https://discourse.channelflow.ch/u/gaw)\
**Replies:** 0\
**Last updated:** [May 29, 2020, 3:27am UTC](https://discourse.channelflow.ch/t/odd-results-with-benchmark-times/97 "2020-05-29T03:27:47Z")

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I have the code installed and running and wanted to get a sense of the speed with a time benchmark. I am running a flow with Nx = 96, Ny = 129, and Nz = 80. I started to get some odd results so I put together an experi…

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## [Randomfiled seed](https://discourse.channelflow.ch/t/randomfiled-seed/84)

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**Author:** [@PratikAghor](https://discourse.channelflow.ch/u/PratikAghor)\
**Replies:** 3\
**Last updated:** [May 27, 2020, 7:21am UTC](https://discourse.channelflow.ch/t/randomfiled-seed/84 "2020-05-27T07:21:04Z")

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Hi all, When I was trying to generate a bunch of randomfields, I observed that the randomfield command was generating the same field again and again. As it turned out, the seed for random numbers was set to default 1. …

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## [Cannot find NeTCDF](https://discourse.channelflow.ch/t/cannot-find-netcdf/94)

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**Author:** [@gaw](https://discourse.channelflow.ch/u/gaw)\
**Replies:** 2\
**Last updated:** [May 26, 2020, 4:09pm UTC](https://discourse.channelflow.ch/t/cannot-find-netcdf/94 "2020-05-26T16:09:22Z")

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I am trying to do an installation and failing. I installed all packages including netcdf on my fedora machine. I installed with the command sudo install netcdf then when I do the command sudo dnf repoquery -l netcdf I ca…

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## [Examples for finding TW solutions with findsoln](https://discourse.channelflow.ch/t/examples-for-finding-tw-solutions-with-findsoln/89)

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**Author:** [@Sjter](https://discourse.channelflow.ch/u/Sjter)\
**Replies:** 2\
**Last updated:** [March 31, 2020, 1:07am UTC](https://discourse.channelflow.ch/t/examples-for-finding-tw-solutions-with-findsoln/89 "2020-03-31T01:07:37Z")

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I’ve been trying to obtain traveling wave solutions to plane Poiseuille flow using findsoln, but have been unable to get a converged solution. I was trying to obtain the results presented in “Exact coherent states and co…

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## [Limit of Reynolds number](https://discourse.channelflow.ch/t/limit-of-reynolds-number/88)

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**Author:** [@arshankhaniitr](https://discourse.channelflow.ch/u/arshankhaniitr)\
**Replies:** 1\
**Last updated:** [March 23, 2020, 10:30pm UTC](https://discourse.channelflow.ch/t/limit-of-reynolds-number/88 "2020-03-23T22:30:48Z")

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Up to what limit of the value of Reynolds number. The code gives the correct result. Regards Arshan Khan Email: akhan@ma.iitr.ac.in

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## [Stratified ECS at high Prandtl number](https://discourse.channelflow.ch/t/stratified-ecs-at-high-prandtl-number/63)

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**Author:** [@jlangham](https://discourse.channelflow.ch/u/jlangham)\
**Replies:** 2\
**Last updated:** [March 22, 2020, 7:25pm UTC](https://discourse.channelflow.ch/t/stratified-ecs-at-high-prandtl-number/63 "2020-03-22T19:25:15Z")

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Hi all, We have a paper out on arXiv in which some of the computations were done with Channelflow 2.0 modified to support density stratification. https://arxiv.org/abs/1904.04853 It is mainly about the generic tendenc…

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## [Channnelflow 2.0 make fail](https://discourse.channelflow.ch/t/channnelflow-2-0-make-fail/73)

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**Author:** [@hemanta](https://discourse.channelflow.ch/u/hemanta)\
**Replies:** 2\
**Last updated:** [January 15, 2020, 10:23pm UTC](https://discourse.channelflow.ch/t/channnelflow-2-0-make-fail/73 "2020-01-15T22:23:04Z")

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I am getting the following error while running “make -j” command, It seems that HDF5 library link error. … \[ 41%\] Linking CXX executable simulateflow …/channelflow/libchflow.so: undefined reference to H5Gopen1' ../cha…

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## [2D flow simulations](https://discourse.channelflow.ch/t/2d-flow-simulations/76)

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**Author:** [@Vilda](https://discourse.channelflow.ch/u/Vilda)\
**Replies:** 5\
**Last updated:** [September 12, 2019, 8:48pm UTC](https://discourse.channelflow.ch/t/2d-flow-simulations/76 "2019-09-12T20:48:18Z")

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Hi, I was wondering if it’s possible to adapt Channelflow for purely 2D configurations? It doesn’t seem that Nz=0 is supported. Thanks for your help, Vilda

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## [Independent velocities at the two walls](https://discourse.channelflow.ch/t/independent-velocities-at-the-two-walls/62)

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**Author:** [@laurette](https://discourse.channelflow.ch/u/laurette)\
**Replies:** 2\
**Last updated:** [September 11, 2019, 6:03pm UTC](https://discourse.channelflow.ch/t/independent-velocities-at-the-two-walls/62 "2019-09-11T18:03:52Z")

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Another option I am interested in is the possibility of setting the wall velocities independently, rather than having +- Uwall at the two walls. This would be useful for studying Poiseuille flow with in a frame with no m…

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## [Recommendations for -np0 and -np1](https://discourse.channelflow.ch/t/recommendations-for-np0-and-np1/33)

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**Author:** [@john.gibson](https://discourse.channelflow.ch/u/john.gibson)\
**Replies:** 3\
**Last updated:** [September 5, 2019, 4:00pm UTC](https://discourse.channelflow.ch/t/recommendations-for-np0-and-np1/33 "2019-09-05T16:00:39Z")

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I’m running channelflow on a cluster with 28 compute nodes. Each node has two 12-core Xeon E5-2680 CPUS. I envision two scales of channelflow computations: small, running on one node with 24 cores, 128 x 129 x 128 dis…

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