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Usage of CFD techniques and visualization in Sphinx preservation

01 Jan 2007 - 01 Jun 2008

 The Great Sphinx is a monumental statue that is considered the first truly colossal sculpture in Egypt and a national symbol of both ancient and modern Egypt. The statue would have disappeared long ago had it not been buried under sand for so long. The statue is eroding due to the effects of wind, humidity and the smog from Cairo. Wind is one of the most critical denudation factors that are causing the erosion of the statue, especially when it carries dust.

A textured model for Sphinx and the Giza Plateau
In order to investigate the formation of the low speed wind over the Sphinx model, a simulation is made involving solving the 3D incompressible Navier-Stokes equations on a several millions of points’ computational mesh. The VISTA team has implemented the visualization of the simulation results on the CAVE system using Avizo® to provide new insights and better understanding. The visualization involves several visualization algorithms: Stream Ribbons The CAVE system helped the scientists to study some phenomena, such as the secondary phenomena at the at corners and cavities of the left of the statue. It was not possible to study such phenomena using traditional methods.
The secondary phenomenon visualized via Stream Ribbons can be studied in a better way on the CAVE system
Line Integral Convolution (LIC) Algorithm
This algorithm is useful to visualize the shape of the air flow as well as the pressure values. This helps to emphasize the non-existence of dynamic load due to low speed northwest wind acting on the head.
The LIC plane visualized both the air field shape and the pressure values using colors
Illuminated Stream Lines (ISL) Algorithm
This algorithm provides a 3D animated representation of the whole air flow field. The CAVE system allows the user to get immersed inside the ISL field, which gives better insights and hence understanding of it rather than the 2D screens.
The air flow can be represented in 3D via animated Illuminated Streamlines. Also the pressure values on the Sphinx surface can be mapped to colors.
The vorticity magnitude on the surface of the statue, which is a measure of the friction stress, is visualized as color contours on the Sphinx surface. The Sphinx’s weak areas, which are the left shoulder and the top of the hunches, are exposed to maximum wind friction. The back of the head and the top of the trunk are also considered vulnerable areas.
Vorticity magnitude on the Sphinx surface is mapped to colors.


Research Fields

Virtual Cultural Heritage

Virtual Cultural Heritage is a research field that aims to use modern computer graphics...