Contact

Dr. Natalia Shevchenko
Magnetohydrodynamics
n.shevchenkoAthzdr.de
Phone: +49 351 260 3313

Radioscopic method

X-ray radiography is an absorption-based imaging technique. A series of radiographic images recorded in real time with an acceptable time resolution is known as radioscopy. It was successfully applied in recent years for investigations of diffusion and flow phenomena in liquid metals, solidification and metal foaming processes.


Figure 1: Principle of radiography

X-ray attenuation along path dx: dI = -µ·I·dx;

µ is X-ray attenuation coefficient / a function of X-ray energy and of the material (density, composition, phases…).

I = I0 exp(-µ·x) the Beer-Lambert law of attenuation or the Beer–Lambert–Bouguer law.

The X-ray radioscopy delivers a two-dimensional projection of the local density in the slit container corresponding to the distribution of the relative brightness P in the acquired images. For instance, this method provides a two-dimensional visualisation, revealing transient changes in the local composition of the solidifying In-Ga alloy. An estimate of the flow field ahead of the solidification front has been obtained by analyzing the motion of brightness contours corresponding to gradients in the solute distribution (Fig 2a). Other interesting application concerns the field of liquid metal two-phase flows focusing on bubble formation or bubble motion in a bulk liquid (Fig. 2b).


Figure 2: a) Snapshot of the dendritic structure with reconstructed melt flow using the Optical Flow approach; b) Bubbly flow – raw image and after data processing.

Selected publications:


Contact

Dr. Natalia Shevchenko
Magnetohydrodynamics
n.shevchenkoAthzdr.de
Phone: +49 351 260 3313