Professor Mojtaba Ghadiri


Engineering Science of Processes involving Particulate Matter

Attrition, comminution, agglomeration, dispersion, compaction, nanopowder processing, electrical effects, mechanics of particle motion and super-critical fluid processing

The focal point of my work is the development of relationships between microscopic and macroscopic properties and phenomena; i.e. the way in which the microstructure of particulate solids and the micromechanics of their behaviour in process equipment influence the performance of the process and the characteristics of the product.  The ultimate objective is to provide a basis for systematic design of particulate products and of related processes.

Research interests

Attrition and Comminution: Damage mechanics of particulate solids is being investigated in relation to attrition and comminution, and erosion and abrasion of surfaces.  Current work includes attrition of granules and encapsulates, milling and processing of pharmaceutical powders.  The emphasis is on the characterisation of single particle damage under impact and quasi-static loading.  Application of the results to the analysis of macroscopic bulk behaviour is done by the use of Distinct Element Analysis.

Agglomeration: The influence of scaling-up of the high shear mixer granulators on the evolved structure of granules is under investigation in a large multi-tasks project addressing experimental and modelling aspects of the flow field within the granulator and the characteristics of the granules formed as influenced by the scale of operation.

Electrical Effects: Work on this line originates from the development of the Electromechanical Valve for Solids (EVS), which is a novel device for flow control of granular materials using the electrical clamping phenomenon.  Current work addresses the coalescence of water droplets in oils, electro-spraying and prilling of highly viscous suspensions to reduce andcontrol the droplet size and tribo-charging of pharmaceutical powders.

Powder Mechanics: The current activity aims to relate the macroscopic bulk behaviour to single particle properties for the analysis of flow, segregation, compaction, dispersion and mixing.

Nanopowder Processing Work on this line addresses the formulation of granules formed by nano-assemblies having optimum re-dispersion characteristics.

Supercritical Fluid Processing Spray coating of surfaces by droplets/fine particles and formation of fine powders by several methods using super-critical fluids is under development.