WSCG 2010, Plzen, Czech Republic LOUISIANA STATE UNIVERSITY

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1 Evolving Time Surfaces in a Virtual Stirred Tank Bidur Bohara, Farid Harhad, Werner Benger, Nathan Brener, S. Sitharama Iyengar, Bijaya B. Karki, Marcel Ritter, Kexi Liu, Brygg Ullmer, Nikhil Shetty, Vignesh Natesan, Carolina Cruz-Neira, Sumanta Acharya, Somnath Roy WSCG 2010, Plzen, Czech Republic LOUISIANA STATE UNIVERSITY 1

2 Outline Overview of Integral Surfaces Dataset & Data Model Generation of Time Surfaces Deployment to End User Conclusion LOUISIANA STATE UNIVERSITY 2

3 Motivation extract the features of flow field from a very large time dependent CFD data set. visualize the spatially evolving features of fluid flow in space-time domain analysis tool for illustrating the movement (dispersions) of particles in a closed stirred tank system LOUISIANA STATE UNIVERSITY 3

4 Motivation stirred tanks commonly used in industries improvements in design can translate into billions of dollars, but better design comes with better understanding of mixing in tank develop tool to analyze the mixing condition in such system LOUISIANA STATE UNIVERSITY 4

5 Related Work Stream surfaces, most commonly investigated technique for surfaces visualization first algorithm given by Hultquist (1992) Krishnan et. al (2009 IEEE), paper discusses the generation of Time and Streak surfaces in Large Time-varying data. planer topology, as compared to our spherical topology LOUISIANA STATE UNIVERSITY 5

6 Time Surfaces over Pathlines Pathlines : most common approach to visualize the flow behavior in fluid system Useful for few particles and for few time-steps. (a) 23 particle system (b) 516 particle system For large number of particles and longer time steps within enclosed flow system Pathlines => Spaghetti LOUISIANA STATE UNIVERSITY 6

7 Time Surfaces over Pathlines analyzing flow field as evolving surfaces is more relevant in context of enclosed system WHAT IS TIME SURFACE? evolving surfaces over time higher-dimensional extensions of time lines ( evolution of seed line) integration of surfaces over time, that can illustrate key flow characteristics ( such as dispersion of particle system in a flow) LOUISIANA STATE UNIVERSITY 7

8 Stirred Tank Dataset Provided by Dr. Sumanta Acharya and Somnath Roy, Department of Mechanical Engineering, Louisiana State University 2088 curvilinear blocks comprised of 3.1 million cells velocity as vector field and pressure as scalar field each time slice has velocity for each grid point in all blocks total of 5700 time steps; 500 GB binary data LOUISIANA STATE UNIVERSITY 8

9 Stirred Tank Dataset CHALLENGES?? handling and processing of the - voluminous - multi-block - non-uniform curvilinear, dataset to generate time surfaces and track set of particles in flow LOUISIANA STATE UNIVERSITY 9

10 Data Model based on concept of Fiber bundle data model internal data structure with six levels, each composing of arrays representing properties of data set Bundle Time Slice Grid Topology Representation Field user only deals with Bundle Grid Field LOUISIANA STATE UNIVERSITY 10

11 Data Model For Stirred Tank data set and Time Surfaces Field Grid coordinates, velocity, pressure, connectivity collection of all Field entities (one Grid object per slice in our implementation) Bundle entire dataset / sequences of Grid objects for all time slices LOUISIANA STATE UNIVERSITY 11

12 Time Surface module inputs : Data Bundle, Grid object with Seeding points and connectivity output : Bundle as collection of Time Surfaces (Grids) F5 Stirred tank data. BUNDLE In : Bundle GRID Integration Out : Grid In : Grid Vector Field Out : Field In : Field Seeding Input GRID Out : Grid In : Grid Surface Computation Out : Grid Seeding Grid = Time Surface Grid In : Grid Time Surfaces as BUNDLE Out : Bundle LOUISIANA STATE UNIVERSITY 12

13 Particle Seeding & Advection seeding input is the set of points and connectivity information among seed points connectivity information is to create the triangle mesh for surface generation the triangular mesh evolves over time, different to spanning surface out of line segment as in Hultquist s approach LOUISIANA STATE UNIVERSITY 13

14 Seeding Input seeds points set of particles lying on the surface of sphere Seeding input as points Seeding input with triangular mesh LOUISIANA STATE UNIVERSITY 14

15 Triangular Mesh Refinement over integration time the triangular mesh of surface enlarges resulting unsmooth evolving surfaces. adaptive surface refinement approach is mandatory for high quality output Surface Refinement Criteria: Edge Length Triangle Area a a d f d c b e c b LOUISIANA STATE UNIVERSITY 15

16 Time Surfaces Evolution of two spheres at time slices 0, 50, 100, 125, & 150 from left-top to bottom. [Top View] LOUISIANA STATE UNIVERSITY 16

17 Out of Core Memory Management partial access and handling of input data Slice-wise sequential access and Block-wise random access each time slice with corresponding Grid Object is processed only once ( Slice-wise) Time surface computed from vector field in 2088 fragments(curvilinear grids) covering the Stirred tank. LOUISIANA STATE UNIVERSITY 17

18 Out of Core Memory Management each Grid object consists of vector field information of 2088 blocks accessing only those blocks that the particles touches at particular time rather than all 2088 blocks( Block-wise) Only the Fragments that affect the evolution of the time surface are loaded in the memory LOUISIANA STATE UNIVERSITY 18

19 Timing Analysis Timing Analysis for Threshold = timesteps, 12 GB Stirred tank data 64 bit quadcore workstation with 64 GB RAM for increasing number of points block-wise memory access reduces per point LOUISIANA STATE UNIVERSITY 19

20 Deployment to End Users VISH ( provides the feature to decouple the user interface from the visualization application. significant portion of interaction through viz tangibles interaction control message triggered by physical events are sent to VISH uses Cartouches (RFID tagged interaction cards) User physically manipulating VISH Application through Viz Tangibles LOUISIANA STATE UNIVERSITY 20

21 Viz Tangibles interaction with both data and operations by appropriate cartouches Current implementation: Viewpoint Controls Parameter Adjustment Controls LOUISIANA STATE UNIVERSITY 21

22 Conclusion an advancement towards exploring the time dependent feature of the fluid flow by generating Time Surfaces of the flow. using software framework VISH and Fiber Bundle data model Slice-wise sequential access and Block-wise random access of input data adaptive refinement of evolving Time Surfaces use of Viz Tangibles(Cartouches) as interfacing tool LOUISIANA STATE UNIVERSITY 22

23 THANK YOU!!! LOUISIANA STATE UNIVERSITY 23