New 3D Flowsquare

The new Flowsquare, Flowsquare+, has been released. The support for the old Flowsquare (introduced on this page) has been discontinued.

Details are available at:

Above video: Room AC (heating) simulation simulated by up-to-date Flowsquare+. The tracer particles are fed from AC, coloured based on temperature (red hot, blue cold). The room configuration and walls are constructed using a Flowsquare+ interface with Microsoft Paint.

Last update: Nov 29th, 2021

What is Flowsquare?

Flowsquare is a two-dimensional computational fluid dynamics (CFD) software for unsteady, non-reactive/reactive flows. The aim of this software is to provide a handy CFD environment so that more people can get to know what CFD is like and simulate flows for their educational and/or academic interests. For example, a typical commercial CFD software costs at least several thousands $ for one license and requires a lot of computational resources and skills. They are untouchable for most of us. Flowsquare is free of charge, and does not require any professional skills, such as programming, CAD, meshing, preprocessing, post-processing; all you need to do is drawing a simple illustration of simulation field using any available paint tool such as Microsoft Paint.

A flow simulation around a car. Draw one or two images using Microsoft Paint (or equivalent), and decide what kind of flow you want to feed from the inlet! Many sample cases and movies are available here.

A flow simulation around a car. Draw one or two images using Microsoft Paint (or equivalent), and decide what kind of flow you want to feed from the inlet! Many sample cases and movies are available here.

What can Flowsquare do?

Using Flowsquare, you can simulate non-reacting flows, reacting flows (both for premixed and non-premixed mixtures) and subsonic/supersonic flows. Unique features of Flowsquare include:

  • Computational domain is set by one or two Bitmap image(s) and one text file.
  • Visualisation is done in real time (in situ) and can be saved as Bitmap files.
  • Various visualisation tools (colours, contours, vectors, graphs and Lagrangian particles) are pre-included (so no additional visualisation tool is needed).
  • Simulation data (binary format) is also available for post-processing.
  • Very flexible numerical scheme and conditions (inflow, wall, periodic and moving boundaries are part of them).
  • Basically free of charge (any supports are welcome!).

Changes made from older version include:

  • Higher order numerical schemes
  • 20 % enhanced computational speed
  • Euler equation for subsonic/supersonic inviscid flows
  • One-dimensional cross-sectional plot for in situ and post analysies
  • More flexible initial and boundary conditions (inc. initial velocity perturbation)
  • More flexible contour plots
  • Post-processing & post-visualisation tools

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+ Non-reacting flows

Various incompressible non-reacting flows are simulated. The simulation can be very accurate (less than 1% difference from the theoretical value for a 2D channel flow simulation with high order scheme) for appropriate numerical settings. Using inflow, wall and/or moving boundaries, practical configuration can also be simulated.

Karman vortex street

Karman vortex street

+ Reacting flows


A Bunsen flame.

Reacting flows (eg. combustion) can be simulated for both premixed and non-premixed configurations under the low-Mach number assumption. For premixed reacting flows, the chemical reaction rate is described using a one-step global reaction based on the Arrhenius law and the parameters can be adjusted appropriately. In this mode, partially-premixed configurations can also be considered. For non-premixed mode, infinite chemistry (mixed is burnt) is assumed. For both configurations, constant thermochemical and transport parameters are used.

+ Subsonic/supersonic flows

Flowsquare ver. 4 can deal with Euler equations for subsonic/supersonic (inviscid) flows. Various supersonic flows are tested to validate the computational accuracy and some of such cases are introduced for Oblique Shock and de Laval Nozzle configurations. The solutions obtained using Flowsquare differ only 1-2% from theoretical values for tested conditions.

A jet flow.

A jet flow.

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User Cases

Flowsquare is used in all over the world by individuals, educational institutes and companies for a variety of purposes. Some users send me feedbacks so I can know what kind of people use the Software. Here is a part of the list of places where Flowsquare is used and their purposes of the use. No particular order.

  • Tokyo Institute of Technology: Lecture
  • Meijo University: Lecture
  • Tokyo University of Agriculture and Technology: Research
  • University of Stuttgart: Research
  • Wakaida Engineering inc.: Initial product analysis
  • General Electric (GE): Employee training
  • Gifu National College of Technology: Research
  • Kumamoto University: Research
  • University of Pennsylvania: Design project (architecture)

Students and staff from following research and educational institutes applied the Student licenses (as of November 2014, no particular order):

  • USM Malaysia / AICET / Hydraulics, Ecole Hassania des Travaux Publics / University at Buffalo / Kobe University / Nihon University / Symbiosis International University / Hochschule Furtwangen University / Japan Aviation Academy / University College London/ University of Nantes / Baghdad university / University of Kyoto / Sycamore Tree Academy / NIT-Surat / University of North Carolina at Charlotte / Tokyo University of Agriculture and Technology / Open University / University of Tokyo / Waseda University / Saint Louis University / The Hong Kong University of Science and Technology / Cardiff University / University of Huddersfield / Kushiro National College of Technology / Tokyo University of Science / Universitas Pendidikan Indonesia / Uniwersytet Jagielloński w  Krakowie / University of the Philippnes Diliman / University of Minnesota / University of Pretoria / Chuo University / University Malaysia Pahang / CAChemE – Universidad de Alicante / Hoso University Yokohama National University / University of Detroit Mercy / Tokyo Institute of Technology / University of Arizona / Gifu University / University of Colorado / University of Leon / Tohoku University / University at Buffalo / Kyoto Institute of Technology / Universidad de Los Andes / The Chiba Prefectural High School/ Kinki University / Universiti Malaya / California Polytechnic State University / Nagoya Municipal Technical High School / Marche Polytechnic University / Loughborough university / Gunma University / Ritsumeikan Moriyama Senior High School / Ritsumeikan University / Hochschule Bremen / University of Calgary / University of Melbourne / Matsue National College of Technology / Chiba University / Tokai University / Brno University of technology / University of Greenwich / University of Toyama / Inholland University of Applied Sciences / Chiba Institute of Technology / Amity University / Guru Gobind Singh Indraprastha University / Kanazawa Institute of Technology / Richview Collegiate Institute / Stellenbosch University / Niihama National College of Technology

Also, see what other users say about Flowsquare on Twitter!

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Please download the software and/or documentation from the link below.

License Agreement: There are three license types for Flowsquare 4.0 (the software): Free license, Donation license, and Student license. Once users installed the software, they are initially Free license holders. The Free license has no functional restriction except for computational speed (See License Types). The users can use the software (with any license types) to simulate and analyse flows, and use the results in private and in public, for non-commercial and for commercial purposes.

Disclaimer of Warranty: You agree and acknowledge that your use of Flowsquare 4.0 (the software) is entirely at your own risk, and that the developer of the software makes no implied or express warranties about the reliability of the software. The developer of the software is not responsible for any damages caused by or resulting from the use of the software.

  • Flowsquare ver 4.0 (free): (executable file) – 1.16 MB
    for Windows Me, 2000, XP, Vista and 7 (haven’t tested on Win 8, but it may work…)
    Note this file does not contain README or manual. Go to tutorials from the link on the top of this page.
  • Input files: – 2.74 KB
    For those who need to get back to the default setting (already included in above
  • Users’ Guide: Theory and Computation – 913 KB
    Don’t be overwhelmed by this. For now, most of you don’t need to go through the background theory. Let’s move on to Lesson 1!

Installation: Once download is complete, unzip, and you will find flowsquare.exe, bc.bmp and grid.txt in the directory. These files are already set up for a simulation of 2D channel flow, so simply double click flowsquare.exe to start your first simulation!

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If you are happy with it, why not support Flowsquare? The donation can be done from the following link easily and safely, by using your PayPal account or credit/debit card. You can choose the amount of donation.

After the payment, you will be redirected to a web page which shows a password to unlock the software under the Donation license (if not, please send me an email with your payment details such as date, amount, etc). A confirmation number of your payment is NOT a password. There are also Student Licenses to unlock the software (see details Student License).

Note: Sending donations does NOT mean I (the developer of Flowsquare) am responsible for any damages resulting from the use of the software, supports or updates of the software. The payment is NOT refundable.

Donate from the following link securely via PayPal:
Donate Button with Credit Cards
Thank you so much for your support!

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Related Events

  • 31st March 2014 [Log]
    CFD Online Tutorial (Hyogo, Japan ←→University of Pennsylvania/Department of Architecture)

  • 22nd-23rd February 2014 [Activity report (Japanese)]
    CFD Programming Seminar (Tokyo)

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(Not all) About Us

Name: Yuki Minamoto, Ph.D. Cantab
Roles: Developer and Webmaster
Living place: Kanagawa, Japan
Email: flowsquare[ATMARK]
Key areas of interests and expertise: Turbulent reacting flows, fluid dynamics, heat transfer, high performance computing (MPI and GPGPU), laser diagnostics (SPIV and PLIF), and cycle race (road/track)
Languages: Japanese (native), English, c, c++, Fortran, CUDA, Matlab, HTML, LaTex
Work/Education: Tokyo Institute of Technology (assistant professor, September 2015–present) / Sandia National Laboratories (postdoc, June 2014–August 2015) / PhD in Engineering from University of Cambridge (St John’s College, awarded in February 2014) / MEng from Tokyo Institute of Technology (March 2010) / BEng from Tokyo Institute of Technology (March 2008)

Contact me from the above email address or below contact form if you have any enquiries or comments regarding Flowsquare.

Name: Manuel Fermin Fonseca
Role: Translation for Spanish page.
Living place: Valencia, Venezuela
Email: manuelffonseca[ATMARK]
Key areas of interests and expertise: Fluid dynamics, heat transfer, mechanical design, Autocad, Ansys, open-source software, turbomachinery, steam engines, green technology, aircraft, ships
Languages: Spanish (native), English, Visual Basic, Matlab.
Education: Msc. Mechanical Engineering — (in course) Mechanical Engineer — August 2005 (Carabobo’s University)
Cualquier recomendación acerca de la traducción pueden escribir al administrador.

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