Texture Advection on Stream Surfaces: A Novel Hybrid Visualization Applied to CFD Simulation Results

Stream surfaces are a classic flow visualization technique used to portray the characteristics of vector fields, and texture advection research has made rapid advances in recent years. We present a novel hybrid visualization of texture advection on stream surfaces. This approach conveys properties of the vector field that stream surfaces alone cannot. We apply the visualization technique to various patterns of flow from CFD data important to automotive engine simulation including two patterns of in-cylinder flow (swirl and tumble motion) as well as flow through a cooling jacket. In addition, we explore multiple vector fields defined at the stream surface such as flow, vorticity, and pressure gradient. The results of our investigation highlight both the strengths and limitations of the hybrid stream surface-texture advection visualization technique and offer new insight to engineers exploring and analyzing their simulations.

A hybrid visualization of texture advection on a stream surface. Texture is animated according to the flow field. Color is mapped to flow magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

A hybrid visualization of texture advection on a stream surface. Texture is animated according to the flow field. The blue-yellow color is map reduces visual complexity and facilitates perception of the surface.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

Texture is animated according to the vorticity field. Such a visualization lets the engineer explore the relationship between velocity and vorticity. The blue-yellow color is mapped to vorticity magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

Texture is animated according to the pressure gradient field. Such a visualization lets the engineer explore the relationship between velocity, vorticity, and pressure gradient in a novel way. The blue-yellow color is mapped to pressure gradient magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

A hybrid stream surface-texture advection visualization showing tumble motion inside a gas engine cylinder. Texture is advected according to the velocity field and color is mapped to velocity magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface as on the left but with a simpler color scale to facilitate perception. Texture is advected according to the velocity field and color is mapped to velocity magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface geometry. Texture is advected according to the vorticity field and color is mapped to vorticity magnitude. The relationship to the velocity field can be explored in a novel fashion.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface as on the left but with a simpler color scale to facilitate perception. Texture is advected according to the vorticity field and color is mapped to vorticity magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface geometry. Texture is advected according to the vorticity field and color is mapped to helicity. Mapping color to helicity indicates candidate vortex core regions.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

Texture is advected according to the velocity field and color is mapped to velocity magnitude. An improved color mapping aids perception.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

Texture is advected according to the vorticity field and color is mapped to vorticity magnitude, with an improved color mapping.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

Texture is advected according to the pressure gradient field and color is mapped to pressure gradient magnitude. An improved color mapping aids perception.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface geometry. Texture is advected according to the pressure gradient field and color is mapped to pressure gradient magnitude. The relationship to the velocity or vorticity fields can be explored.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface as on the left but with a simpler color scale to facilitate perception. Texture is advected according to the pressure gradient field and color is mapped to pressure gradient magnitude.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

A stream surface geometry generated with different seeding parameters and an alternative color mapping visualizing tumble motion. The texture properties and color mapping reflect the vector field characteristics.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface geometry but with texture properties and color mapped to vorticity.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

The same stream surface geometry but with texture properties and color mapped to the pressure gradient field.
[MPEG animation] 900 frames, 512x512 resolution (~6 MB).

A hybrid stream surface-texture advection visualization depicting the characterstic flow through a cooling jacket. In this case a red and blue have been mapped to opposite sides of the stream surface in order to aid perception of vortical characteristics. Both texture and color depict the flow field.
[MPEG animation] 900 frames, 512x512 resolution (~7 MB).

A hybrid stream surface-texture advection visualization depicting the characterstic flow through a cooling jacket. A conventional color map has been used. Both texture and color depict the flow field.
[MPEG animation] 1000 frames, 512x512 resolution (~7 MB).

The same stream surface geometry except this time the fluid conduits in the cooling jacket gasket are shown. A conventional color map has been used. Both texture and color depict the flow field.
[MPEG animation] 500 frames, 512x512 resolution (~3.5 MB).