[1] Heriot Watt Univ, RCCS, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Midlothian, Scotland
[2] Imperial Coll London, Dept Mech Engn, London SW7 2AZ, England
[3] Loughborough Univ, Dept Chem Engn, Loughborough, Leics, England
[4] Aston Univ, Sch Engn & Appl Sci, Birmingham, W Midlands, England
[5] Heriot Watt Univ, Sch Social Sci, Edinburgh EH14 4AS, Midlothian, Scotland