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Numerical simulation can provide detailed understanding of mass transport within complex structures. For this purpose, numerical tools are required that can resolve the complex morphology and consider the contribution of both convection and diffusion. Solving the Navier–Stokes equations alone, however, neglects self - diffusion. This influences the simulated displacement distribution of flow especially in porous media at low Péclet numbers (Pe < 16) and in near-wall regions where diffusion is the dominant mechanism. To address this problem, this study uses μCT-based computational fluid dynamics (CFD) simulations in OpenFOAM coupled with the random-walk particle tracking (PT) module disTrackFoam and cross-validated experimentally using pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) measurements of gas flow within open-cell foams (OCFs). The results of the multi-scale simulations—with a resolution of 130–190 µm—and experimental PFG NMR data are compared in terms of diffusion propagators, which are microscopic displacement distributions of gas flows in OCFs during certain observation times. Four different flow rates with Péclet numbers in the range of 0.7–16 are studied in the laminar flow regime within 10 and 20 PPI OCFs, and axial dispersion coefficients were calculated. Cross-validation of PFG NMR measurements and CFD-PT simulations revealed a very good matching with integral differences below 0.04%, underpinning the capability of both complementary methods for multi-scale transport analysis.

Summary Background Wound healing deficits and subsequent surgical site infections are potential complications after surgical procedures, resulting in increased morbidity and treatment costs. Closed-incision negative-pressure wound therapy (ciNPWT) systems seem to reduce postoperative wound complications by sealing the wound and reducing tensile forces. Materials and methods We conducted a collaborative English literature review in the PubMed database including publications from 2009 to 2020 on ciNPWT use in five surgical subspecialities (orthopaedics and trauma, general surgery, plastic surgery, cardiac surgery and vascular surgery). With literature reviews, case reports and expert opinions excluded, the remaining 59 studies were critically summarized and evaluated with regard to their level of evidence. Results Of nine studies analysed in orthopaedics and trauma, positive results of ciNPWT were reported in 55.6%. In 11 of 13 (84.6%), 13 of 15 (86.7%) and 10 of 10 (100%) of studies analysed in plastic, vascular and general surgery, respectively, a positive effect of ciNPWT was observed. On the contrary, only 4 of 12 studies from cardiac surgery discovered positive effects of ciNPWT (33.3%). Conclusion ciNPWT is a promising treatment modality to improve postoperative wound healing, notably when facing increased tensile forces. To optimise ciNPWT benefits, indications for its use should be based on patient- and procedure-related risk factors.