Figure 4
Double c-type bipolar MHDE. (a) A double bipolar MHDE. \(\overrightarrow{B}\): magnetic flux density, \(\overrightarrow{u}\): velocity, \(\overrightarrow{i}\): current density, C: cathode, A: anode. (b) A bird’s-eye view of a double c-type bipolar MHDE. (c) A bird’s-eye view of a double c-type bipolar MHDE with a diffuser. (i): cathode, (ii): anode, (iii): MHD flow, (iv): diffuser (plastic net). 
: negative vacancy, 
: positive vacancy, 
: cross section of the wire of net, curled lines in the magnified view in Fig. 4c: Kármán vortexes.
