A software package TURCOM has been developed to visualize the results of 2-d fluid dynamics modelling on non-structured grids. This software is written in the PV-WAVE command language [1] and runs on most graphic workstations. Calculations are performed of chemically reacting gases within containers of variable geometry [2]. A database is used to store the results together with the grid geometry [3]. This database is accessed by TURCOM via mouse-driven menus and icons. An objective of this work has been to avoid interpolation onto regular grids. Therefore some new algorithms have been developed to present the results of model calculations graphically. Scalar fields can be displayed as iso-contours or as colour shaded iso-plots. Vector fields can be displayed as vector flows with or without a scalar colour index. Visualization of the time evolution of data is also possible. Introduction A research project for the Numerical Simulation of Reactive Gas Flows [4] is in progress at the JRC-lspra. It's primary aim is. to predict the development of explosions in confined or semi-confined environments. This involves simulating shock wave propagation and reflection from container walls. The calculations are performed on a non-structured grid in two dimensions. Complex geometries are defined by a mesh of node points and by triangular finite elements. Two examples of such mesh grids are shown in fig.1. In general a 2-d non-structured grid can be defined as follows: #„,*,;• = 1, a) / (C,c,c.) j = i,N (2) Transactions on Information and Communications Technologies vol 5, © 1993 WIT Press, www.witpress.com, ISSN 1743-3517 406 Visualization and Intelligent Design where: N^ = no. of nodes, x= position vector of node i Ny = no. of triangular elements , C /2// ) = end node indices for j th face in the i th boundary Some further geometric properties of such triangular grids are found to be useful. These are indexed for each node and deduced by a sorting procedure. They are: L} = 0: if node is internal = m: if it forms part of boundary m NP= number of triangles with this node as a vertex { V .. } = triangle index connecting this node ji j = i,MP. ^ ordered anti-clockwise This is illustrated in fig. 2. Transactions on Information and Communications Technologies vol 5, © 1993 WIT Press, www.witpress.com, ISSN 1743-3517 Visualization and Intelligent Design 407 Figure 2 also defines what is known as the control volume for this node. The fluid calculations are discretised within these control volumes. This means that the resultant physical properties for each node point apply for all fluid within the control volume. These control volumes are therefore also important when visualizing the results of calculations. They are defined geometrically as the polygon formed by joining the mid-points of each triangle associated with a given node. The mid-point of each triangle is calculated from the intersection of lines bisecting each angle of the triangle. Many runs of the code REAC are performed. The objective of the work described here has been to organise storage of results and geometry in a database [3] and to develop a sophisticated data visualization system. internal node i