Rudy Swennen mainly investigates Mineralogy, Environmental chemistry, Sediment, Tomography and Soil contamination. His Mineralogy study combines topics from a wide range of disciplines, such as Porosity and Recrystallization. The Environmental chemistry study combines topics in areas such as Leaching, Organic matter and Arsenic.

His Sediment study incorporates themes from Tailings, Dredging, Contamination, Pollution and Heavy metals. His biological study spans a wide range of topics, including Tufa, Carbonate, Calcite, Isotope geochemistry and Facies. His Dolomite study introduces a deeper knowledge of Geochemistry.

His most cited work include:
Applications of X-ray computed tomography in the geosciences (291 citations)
Large deep-water coral banks in the Porcupine Basin, southwest of Ireland (259 citations)
Quantitative analysis of reservoir rocks by microfocus X-ray computerised tomography (184 citations)