1. Mechanical Engineering and Materials Research Centre, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF
2. School of Computing and Mathematics, Keele University, The Covert, Keele ST5 5BG and Department of Mechanical, Chemical and Material Engineering, University of Cagliari, Piazza d’Armi, Cagliari 09123, Italy
3. Department of Mathematical Sciences, University of Liverpool, Peach Street, Liverpool L69 7ZL