Hewitt, Sam

Margetts, Lee

Seu, Eleonora

English

In the engineering world the post processing of CFD simulations is done with tools that are very difficult to use for whoever is not an insider. Moreover, simulations are often heavy and displaying the results may be very time consuming. This is even more true when the simulations are non-steady or in the case of Fluid-Structure Interaction, when it is required to work with the results of every time step and the amount of data grows exponentially, making it impossible to carry out real time exploration of the results. Engineers and researchers therefore require a tool to show to non-experts the results of their work in a way that is easily accessible. VR technology used to be very expensive in the past, and its computational speed very slow. Nowadays, with the introduction of affordable headsets, it provides a cheap and effective communication channel between industries and the scientific world. By selecting a relatively small amount of data to show, we can lighten the load of the simulations and have our interlocutor focus on the results that are most important, also giving them an interactive tool to explore that data. Steps have already been taken in this direction, for example by making an explorable fluid simulation of buildings on a 2D screen. But the work discussed in this paper goes even further and shows how it is possible to couple game engine technology and VR displays to achieve these results. Using the game development platform Unity, it is possible to import the data collected using CFD software and convert them into a 3D VR application

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The University of Manchester ResearchUse of gaming and affordable VR technology for thevisualization of complex flow fieldsDocument VersionOther versionLink to publication record in Manchester Research ExplorerCitation for published version (APA):Seu, E., Hewitt, S., & Margetts, L. (2018). Use of gaming and affordable VR technology for the visualization ofcomplex flow fields. Abstract from 6th European Conference on Computational Mechanics (ECCM 6)7th European Conference on Computational Fluid Dynamics (ECFD 7), Glasgow, United Kingdom.Citing this paperPlease note that where the full-text provided on Manchester Research Explorer is the Author Accepted Manuscriptor Proof version this may differ from the final Published version. If citing, it is advised that you check and use thepublisher's definitive version.General rightsCopyright and moral rights for the publications made accessible in the Research Explorer are retained by theauthors and/or other copyright owners and it is a condition of accessing publications that users recognise andabide by the legal requirements associated with these rights.Takedown policyIf you believe that this document breaches copyright please refer to the University of Manchester’s TakedownProcedures [http://man.ac.uk/04Y6Bo] or contact uml.scholarlycommunications@manchester.ac.uk providingrelevant details, so we can investigate your claim.Download date:09. Jun. 2022USE OF GAMING AND AFFORDABLE VR TECHNOLOGY FOR THE VISUALIZATION OF COMPLEX FLOW FIELDS Authors: Eleonora Seu, Università degli Studi di Padova, Department of Industrial Engineering Sam Hewitt, University of Manchester, School of Mechanical, Aerospace and Civil Engineering Lee Margetts, University of Manchester, School of Mechanical, Aerospace and Civil Engineering Eleonora Seu, Università degli Studi di Padova, Department of Industrial Engineering Sam Hewitt, University of Manchester, School of Mechanical, Aerospace and Civil Engineering Lee Margetts, University of Manchester, School of Mechanical, Aerospace and Civil Engineering 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK EQUIPMENT A personal computer is used to: • Create the CAD model of the wind turbine blade • Run the CFD simulation and collect the data • Create the Android application that will be used  to visualize the streamlines in VR (using Unity3D)  The phone, a Samsung Galaxy S6 will run the application The Samsung Gear VR headset will allow the user to see the streamlines in VR. With the controller it is then possible to move around the simulation and select the turbine grade of rotation to visualize. Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK Converts  geometry into format for Unity Blender Uses the model and the data to build the app Unity Winglet sections vary linearly from NACA 0021 to NACA 0013 from the winglet root station to the winglet tip station To generate the mesh  Gambit Runs the simulation Fluent Script generates curves defining blade Matlab Creates the surfaces of the blade Solid Works Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK CREATION OF THE CAD MODEL The overall computational domain is discretized into two macro volumes:  •  a prismatic outer zone, covering the whole computational domain, presenting a cylindrical/conical opening centered on the turbine axis of revolution, identified as Fixed sub-grid;   • a cylindrical/conical inner zone, revolving at the same angular velocity ω of the turbine, identified as Rotating sub-grid. ω = 560 rpm Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK SIMULATION MODEL Boundary conditions: • symmetry boundary condition for the equatorial plane • freestream wind velocity V∞ = 9 m/s at the domain inlet • atmospheric pressure at the domain outlet K-ω SST turbulence model is used  Under-relaxation factors Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK SIMULATION MODEL Fluent allows user to export pathlines in different formats. In this case «Geometry» type is the easiest one to work with. This creates an .ibl file that contains particle paths in form of a curve. Other data, except the shape of the curve (e.g. pressure, velocity, etc.), are lost. This is done for every grade of rotation of the turbine, resulting in 360 .ibl files. The strings «begin curve» and «end curve» define the beginning and ending of each curve inside the file, and are therefore used to separate the file into an array of curves Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK SIMULATION MODEL A script inside Unity is made to convert the text file into and array of vectors. Each array contains the points (x, y, z) of one curve. Fluent reference system: right handed  Unity reference system: left handed  Unity uses a left handed reference system, with gravity acting on the y axis, instead of the classic right hand system that is used by Fluent. Importing the data as it is would result in having the curves mirrored. This problem is easily overcome by inverting the second and third column while importing the data. Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK IMPORTING THE DATA The construct used to visualize the streamlines is called “Line Renderer”. It’s a component that, attached to a GameObject, draws a line between 2 or more points. Since the line is always continuous, in case of completely separate lines it is necessary to use multiple GameObjects. Empty GameObject that contain all the lines of that angle of rotation Specific line To keep the work organized, for each grade of rotation, an empty GameObject is created that is the parent. This contains all the GameObjects that represent the pathlines for that specific angle. During the visualization, the app will enable or disable the parent according to the angle of rotation of the turbine that is currently visualized. Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK VISUALIZING THE STREAM LINES A simple user interface allows the user to rotate the turbine inside the app. Using the controller it is possible to select a specific angle to visualize, or start the spin of the blade setting the desired speed. Using the controller it is also possible to move around the scene, getting closer or farther away from the blade and looking at the streamlines from different perspectives. Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK USER INTERFACE Problems: • Time needed to collect the data: the CFD simulation is automatically saved every time step. Even so, to collect the data required for the VR app, it is necessary to open every time step of the solution and download the relative data.  • Amount of data: to avoid having too much data to import in the application, making it unavoidably slow, it is necessary to select only the data that is of most interest. Future work will include: • Visualization of pressures and other data on planes that can be moved around using the controller: to reduce the amount of data the best option appears to be the use of spatial data structures, such as the octree. In this way it should be possible to reduce the fluid domain from all the domain of the simulation to the areas that are of interest and the level of detail to a set amount.  • Implementing an app for the visualization of FSI: since in this case the mesh changes at every time step it cannot be imported just once using the standard method. It will be necessary to export the mesh every time using the software used to run the simulation. Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK CONCLUSIONS THANK YOU FOR YOUR ATTENTION Eleonora Seu, Università degli Studi di Padova Sam Hewitt, University of Manchester Lee Margetts, University of Manchester 6th European Conference on Computational Mechanics (ECCM 6) 7th European Conference on Computational Fluid Dynamics (ECFD 7) 11 - 15 June 2018, Glasgow, UK 

Use of gaming and affordable VR technology for the visualization of complex flow fields

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Use of gaming and affordable VR technology for the visualization of complex flow fields

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