Fig. 1. SIV-RAFT neural network

Fig. 2. Deformable convolutional networks

Fig. 3. Iterative attention feature fusion module

Fig. 4. Schematic diagram of drag flume experiment

Fig. 5. Centrelines of negatively buoyant jets

Fig. 6. Distributions of centreline mass fractions in vertical sections of 45° jets. (a) 20D; (b) 30D

Fig. 7. Scalar and velocity fields of 45° jet. (a)(b) Instantaneous scalar field images of two adjacent frames; (c) reference velocity field; velocity fields predicted from scalar fields using (d) SIV-RAFT, (e) PWC-Net, and (f) HS algorithms, respectively

Fig. 8. Error analysis results of jet velocity fields. (a) SIV-RAFT; (b) PWC; (c) HS

Fig. 9. Spectrum analysis of 45° jet. (a) E(k); (b) Eω(k)

Fig. 10. Centreline velocity decay curves of 45° jet

Fig. 11. Distributions of velocity in vertical sections at different centreline distances of 45° jets. （a） 20D； （b） 30D

Fig. 12. Velocity amplitude maps of DNS turbulent flow (t=30). (a) Velocity amplitude map of real DNS; (b) SIV-RAFT; (c) PWC; (d) HS

Fig. 13. Vorticity maps of DNS turbulent flow (t=30). (a) Instantaneous vorticity map of real DNS; (b) SIV-RAFT; (c) PWC; (d) HS

Fig. 14. Velocity spectra of DNS turbulent flow (t=30). (a) Horizontal direction; (b) vertical direction

Fig. 15. Velocity spectrum error of DNS turbulent flow (t=30). (a) Horizontal direction; (b) vertical direction