COUPLING BETWEEN DUALSPHYSICS AND SWASH MODELS AND LATEST APPLICATIONS TO COASTAL ENGINEERING PROBLEMS Dr. Corrado ALTOMARE (Flanders Hydraulics Research / Ghent University) 1 Numerical modelling: WHAT FOR? Physical modelling Flooding Damage 3 basic concepts… Which reality do we want to simulate? Which are the coupling techniques we explored? How efficient and accurate is the coupling? We (I) bet on SPH: why? Violent Non-linearity Wave-object and hydrodynamics Object-object interactions Courtesy of Prof. Peter Troch Disadvantages of (WC)SPH Accuracy Computational cost Noise in density and pressure field NS equations (affecting wave propagation) Boundary conditions (GRAND Weakly Compressible Nature CHALLENGE) Convergence (GRAND Number of Neighbors CHALLENGE) What do we aim at? Accurate wave generation Good wave transformation Reasonable computational cost Accurate and detailed modelling of wave-structure interaction What do we aim at? recently…. DualSPHysics (+ MoorDyn) What do we aim at? Impacts of wave overtopping flows on coastal defenses and buildings along the Flemish coast Layer thickness Physical model 0.06 SWASH 0.04 h h (m) 0.02 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 What do we aim at? time (s) Layer speed 4 2 u u (m/s) 0 -2 200 400 600 800Large1000 domains1200 1400 1600 1800 2000 2200 2400 time (s) Instantaneous wave overtopping discharge 100 Detailed wave50- Multi-scaled modeling structure interaction0 q q (l/s/m) -50 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time (s) Free surfaceLong elevation events at St.6 (toe of dike) 0.2 0.1 eta eta (m) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time(s) Large domains: DONE!! Long events: 1000 waves DONE!! 23.6h runtime (on Tesla K20c ) for 82,541 fluid particles Err (wave height)=-3.5%, Err (spectral period)= +4.7% COUPLING basic principle DualSPHysics Wave propagation model (SWASH) overlap = shifting the generation boundary in DualSPHysics Layer thickness Physical model 0.06 SWASH 0.04 h h (m) 0.02 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 COUPLING with SWASH time (s) Layer speed 4 SWASH=Simulating WAve till Shore 2 NLSW equation u (m/s) 0 model -2 Time domain model200 for400 simulating600 800 non1000 -hydrostatic,1200 1400 1600 free1800-surface2000 2200 and2400 rotational flow. time (s) Instantaneous wave overtopping discharge It simulates accurately100 surface wave and velocity field from deep water. 50 Not suitable to0 deal with abrupt changes of shape of the coastal structures. q q (l/s/m) -50 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time (s) Free surface elevation at St.6 (toe of dike) 0.2 0.1 eta eta (m) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time(s) COUPLING with SWASH (1) (2) Relaxation Zone technique (3) COUPLING with SWASH (1) MB (Moving boundary): Altomare et al (2015) COUPLING with SWASH (1) MB (Moving boundary): Altomare et al (2015) COUPLING with SWASH (2) Relaxation zone (RZ) + damping 푧 [푚] RZ C(푥) damping 푥 [m] 푊푅푍 푣 푥, 푧, 푡 푅푍 = 퐶 푥 푣푡ℎ푒표푟푦 +(1- 퐶 푥 )푣푆푃퐻 COUPLING with SWASH (2) 2푥 2푥 푡푎푛ℎ + 훼 훽 − 푡푎푛ℎ − 훼 훽 − 푡푎푛ℎ 1 + 훼 훽 − 푡푎푛ℎ 1 − 훼 훽 푊푅푍 푊푅푍 퐶 푥, 훼, 훽 = 푡푎푛ℎ 훼훽 − 푡푎푛ℎ −훼훽 − 푡푎푛ℎ 1 + 훼 훽 − 푡푎푛ℎ 1 − 훼 훽 1 Previous function 0.9 a=0.5, ß=1 0.8 a=0.5, ß=9 a=0.5, ß=5 0.7 a=0.1, ß=1 0.6 a=0.9, ß=10 0.5 C 0.4 0.3 0.2 0.1 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 ퟐ풙 푾푹풁 Different C functions α=0.1, β=5 α=0.3, β=5 α=0.5, β=5 α=0.9, β=5 RZ-SWASH 푧 [푚] Velocity field SWASH model Input=H,T,d Run 푥 [m] 0 SPH model 퐷 Input=SWASH model Run damping 푊푅푍 A CASE OF STUDY Wave overtopping of sea dikes with very shallow foreshores DualSPHysics stand-alone SWASH MB (Altomare et al., 2015) Relaxation Zone A CASE OF STUDY DualSPHysics stand-alone MB (Altomare et al., 2015) Relaxation Zone A CASE OF STUDY 퐺푒퐹표푟푐푒퐺푇푋 푇푡푎푛 푋 DualSPHysics stand-alone 푛푝푎푟푡푐푙푒 = 3,389,266 푅푢푛푡푚푒 = 95.62ℎ 푛푝푎푟푡푐푙푒 = 494,388 푥푐표푢푝푙푛 = 31. 25푚 푅푢푛푡푚푒 = 9.95 ℎ MB (Altomare et al., 2015) 푛푝푎푟푡푐푙푒 = 1,269,820 Relaxation Zone 푥푐표푢푝푙푛 = 24.00 푚 푅푢푛푡푚푒 = 22.65 ℎ A CASE OF STUDY MB vs RZ-SWASH Layer thickness Physical model 0.06 SWASH 0.04 h h (m) 0.02 0 Conclusions 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time (s) Layer speed 4 2 u u (m/s) 0 Multi scale -2 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 Multitime (s) phase Instantaneous wave overtopping discharge 100 Long duration 50 0 q q (l/s/m) Large domain Remind our-50 target 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time (s) Free surface elevation at St.6 (toe of dike) 0.2 0.1 eta eta (m) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 time(s) Conclusions Wave Generation COUPLING Wave Absorption Relaxation Zone + SWASH Speed up Accuracy To be continued… .