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Ambit is an open-source multi-physics solver that has been developed over the past several years with the original focus to facilitate mechanics modeling of the cardiovascular system. It encompasses finite strain solid mechanics, supporting various constitutive laws suitable to describe cardiac tissue, lumpedparameter models of the circulatory system, and fluid dynamics in Eulerian and ALE descriptions. The framework further supports the coupling of single-field problems and allows 3D-0D interfacing of fluid or solid regions to lumped networks, as well as full 3D-3D fluid-solid interaction (FSI).
Ambit is written in Python and makes extensive use of the latest finite element library FEniCSx and the PETSc linear algebra suite, guaranteeing state-of-the-art backends and high-Performance capabilities.
Currently, the software is extended to multi-phase fluid dynamics and porous media structures, providing the building blocks for multiscale modeling of electrolytic systems, their degradation mechanisms, and beyond.
All multi-physics couplings are formulated and solved in a monolithic fashion, providing interfaces to design tailored block preconditioners for effectively solving large scale systems. Capabilities and performance are demonstrated on a patient-specific FSI-0D model of the heart using a recently proposed preconditioning strategy and on a multi-phase CFD Cahn-Hilliard Navier-Stokes example.
Polymer membranes are critical functional components in proton-exchange membrane water electrolyzers (PEMWEs), where they simultaneously enable ionic transport, separate reactive gases, and Sustain mechanical loads. Despite their central role, membrane failure remains a key limitation for System reliability and safety, driven by the complex interaction of electrochemical reactions, two-phase flow, transport processes, and material degradation due to mechanical, chemical, and thermal loads. In particular, gas-liquid flow regimes in catalyst layers, porous transport layers, and flow channels strongly influence local pressure, temperature, and concentrations at the membrane interface. These impact the membrane’s hydration conditions, inducing heterogeneous swelling, stress concentrations, and Membrane thinning, which accelerates the aging process.
This contribution presents a multiphysics modeling framework for the simulation-based investigation of membrane degradation and failure mechanisms in PEMWEs, synthesizing ideas from previous works into a novel integrated modeling approach. Two-phase flow in the adjacent porous and free-flow regions is described using porous-media formulations and phase-field computational fluid dynamics, resolving gas generation, saturation, and pressure fields under different operating conditions. The resulting interface quantities are coupled to a porous-mixture-based finite strain membrane model that accounts for hydration-dependent transport and swelling-induced deformation. Damage or failure indicators are introduced to capture the onset of critical membrane degradation driven by cyclic loading, dehydration, or pressure fluctuations.
This modeling concept enables systematic analysis of how operating conditions and flow regimes, including annular or mist-like patterns, contribute to membrane stress and failure risk. The Framework provides a foundation for predictive lifetime assessment and supports the design of more durable and safer electrolyzer systems.
Computational modeling of fluid-structure interaction as well as multiphase fluid flow represent highly relevant approaches for insights into many engineering systems, but few works have thoroughly studied the combined effects from a numerical perspective. To-date approaches are either partitioned schemes or fully Eulerian, limiting solver robustness or resolution of the fluid-solid interface. We present a first unified and monolithic finite element approach to multiphase fluid-structure interaction, where the flow is described by a coupled five-field Cahn-Hilliard Navier-Stokes equation system in Arbitrary Lagrangian-Eulerian (ALE) description, and the structure is governed by finite strain elastodynamics. Unknowns of the resulting six-field system are fluid velocities, pressures, phase field, chemical potential, domain displacements, and structural deformation. Coupling of fluid and solid is achieved with a monolithic Neumann-Dirichlet scheme, where the structure is constrained by fluid kinematics and the fluid receives the reaction forces, circumventing the introduction of a Lagrange multiplier. Avenues for the effective solution of the resulting system are shown, and applications to elasto-capillarity and bubble-membrane interactions in electrolyzers are demonstrated.
Introduction: Mitral regurgitation (MR) is a common valvular disease associated with complications such as pulmonary hypertension, atrial fibrillation, and heart failure. However, its full impact on the cardiovascular system, especially on right heart function, is not yet fully understood. Understanding this relationship is important because the right ventricle (RV) is critical for maintaining cardiovascular function. Dysfunction of the RV, which may be contributed by conditions like MR, is strongly associated with poor clinical outcomes. Despite its importance, comprehensively studying MR's effect on the RV has been challenging due to the complex, interdependent nature of cardiovascular dynamics, limited patient data, and the difficulty in synthesizing disparate information to clarify the left heart-right heart connection.
Methods: The primary goal of this study is to investigate the effects of MR on cardiovascular hemodynamics and RV function by integrating 3D models of the left heart with a closed-loop 0D models of the entire cardiovascular system. We further conduct detailed analyses using patient-specific models to explore how various system modifications impact the RV, providing insights into the nuanced effects of MR on the right heart.
Results and Discussion: This analysis provides several clinically relevant insights. First, progressive MR markedly increases RV afterload and predisposes the RV to dysfunction, even when intrinsic RV contractility is preserved or enhanced. Second, MR-specific severity indices and left-heart metrics alone fail to capture the true burden on the right heart; RV impairment can progress despite stable or only modestly changing MR descriptors. Finally, these findings highlight the need to incorporate direct assessment of RV structure and function into the evaluation of MR, as RV vulnerability plays a critical role in determining patient risk and guiding management decisions.
We present a fully coupled, patient-specific 3D–0D computational framework for hearts supported with left ventricular assist devices (LVAD) that enables controlled in silico experimentation. The approach monolithically integrates three-dimensional CFD of the left ventricle (LV), left atrium (LA), aortic root, and LVAD cannulae with a closed-loop 0D lumped parameter network of the full circulation. Mitral and aortic valve dynamics are governed by transvalvular pressure and flow with patient-specific regurgitant orifice areas, and the LVAD is represented via a pressure–flow (H–Q) relation. This manuscript provides the complete mathematical formulation, coupling strategy, and parameterization required to build a reproducible pipeline from dynamic CT, 2D transthoracic echocardiography, and right heart catheterization. This methodology is demonstrated in a patient under long-term support of LVAD and concomitant mitral and aortic regurgitation. The personalized, fully coupled 3D–0D models reproduced available clinical targets with a mean error of 8.6%, enabling controlled in silico interrogation of valve repair strategies. In the patient-specific state, simulated mitral and aortic regurgitant volumes were 6.6 and 6.5 mL per cycle, yielding a forward cardiac output of 3.16 L/min despite an LVAD flow of 3.7 L/min. In silico isolated mitral valve (MV) repair, isolated aortic valve (AV) repair, and combined MV+AV repair increased forward output to 3.41, 3.33, and 3.55 L/min, respectively; however, aortic valve opening and increased aortic pressure pulsatility (up to 38.9 vs. 13.5 mmHg) were observed only when MV repair was involved. These left-sided improvements propagated through the cardiopulmonary circulation, reducing pulmonary pressures and right ventricular loading, with the largest benefit observed following combined repair. We show that the modeling platform presented provides a powerful means to study mechanical circulatory support, enabling patient-specific evaluation of surgical interventions in patients with LVAD and delivering quantitative insight into clinically important metrics—such as aortic pulsatility, RV afterload, and chamber-level flow patterns.
The shock wave generator (SWG) is used to investigate the effects of blasts on humans and structures. Since its explosion characteristics deviate from the ideal characteristics in the form of excessively high impulse, various sensors were used to gain more detailed insights into the combustion and fluid mechanics inside the SWG. Two symmetrically arranged pressure sensors enabled the analysis of the almost identical but slightly shifted propagation of the shock waves inside the SWG, which differs by a few microseconds in time of arrival. The fluid then flows out of the SWG. In this way, the event was detected in a smaller pipe section using a pressure sensor and a fast heat flux sensor. The innovative measurement technology, an Atomic Layer Thermopile Sensor based on the inverse Seebeck effect, enabled the detection of extremely high heat fluxes exceeding 100 MW/m² with MHz-range temporal resolution. This made it possible to resolve the local boundary layer development, which transitioned from laminar to turbulent flow in less than 100 microseconds. In addition, the combination of both sensors allows conclusions to be drawn about the non-ideal shock wave characteristics outside the SWG, i.e. in the area where the models to be investigated are positioned. This makes it possible to identify additional shock waves emerging from the SWG, providing valuable information for further developing and optimising the test setup.
Ein Berliner Galvanikbetrieb verwendet „Chemikalien, wie z.B. Cyanidsalze, cyanidische Lösungen und Salpetersäure“, die dem Anwendungsbereich der Störfall-Verordnung unterfallen. 2015 ordnete die Berliner Senatsverwaltung für Stadtentwicklung und Umwelt die (sofort vollziehbare) Installation einer Brandmeldeanlage an. 2017 installierte der Galvanikbetrieb eine Brandmeldeanlage – allerdings ohne die in der Anordnung geforderte automatische Aufschaltung der Berliner Feuerwehr.
Was lehrt der Fall?
-> Begründung der Erforderlichkeit einer automatischen Brandmeldeanlage für Galvanikbetriebe als „Orte gesteigerter Brandgefahr“ unter Berufung auf Immissionsschutzrecht, TRGS und ASR;
-> Verwaltungsgericht Berlin: „Der Umstand, dass jahrzentelang kein Feuer ausgebrochen ist, stellt lediglich einen Glücksfall dar, dessen Ende jederzeit möglich ist.“;
-> Schlüsselsatz: „Der Stand der Sicherheitstechnik im Bereich des vorbeugenden Brandschutzes im maßgeblichen Zeitpunkt des Jahres 2015 ist im Land Berlin eine automatische Brandmeldeanlage mit direkter und unmittelbarer Aufschaltung auf die Berliner Feuerwehr.“;
-> Anordnung der Behörde ist verhältnismäßig – trotz des Kostenrisikos bei Fehlalarmen, das der Galvanikbetrieb zu tragen hat.
Der folgende Beitrag der Bundesanstalt für Materialforschung und ‑prüfung (BAM) zeigt Ergebnisse von Untersuchungen zur Prüfung des Initiierungsvermögens leistungsstarker pyrotechnischer Anzünder für Fahrzeuge der Kategorie P1 gegenüber kapselempfindlichen Sekundärsprengstoffen. Hintergrund ist die Umsetzung der wesentlichen Sicherheitsanforderungen (ESR) 4 b) und c) der Richtlinie 2013/29/EU, wonach pyrotechnische Gegenstände der Kategorie P1 weder selbst detonierend funktionieren noch Sekundärsprengstoffe zünden dürfen, Gegenstände der Kategorie P2 zwar detonierend funktionieren dürfen, jedoch keine Sekundärsprengstoffe selbst zünden können. Die Prüfungen erfolgten im Kontext der laufenden Normungsarbeiten zur Norm E DIN EN ISO 14451:2026-02 bzw. prEN ISO 14451:2026 (D) Teile 2-10 und orientierten sich an der dort in Teil 2 beschriebenen Prüfmethode, die so auch in Entwürfen für andere Normenreihen für pyrotechnische Gegenstände zu finden ist. Abweichend von dem Vorschlag des Normentwurfes wurde für diese Untersuchungen der plastische Sprengstoff NSP711 (PETN-basiert) ausgewählt, da Voruntersuchungen zeigten, dass dieser im Vergleich zu RDX (phlegmatisiert mit Wachs) eine höhere Reibempfindlichkeit besitzt und damit ein kritischeres, sicherheitsrelevantes Worst‑Case‑Szenario darstellt. Die Initiierungsversuche wurden mit jeweils 25 g NSP711 durchgeführt. Untersucht wurden zwei handelsübliche, energiereiche pyrotechnische Gegenstände aus der Fahrzeugpyrotechnik (Igniter 535 mg und Initiator 260 mg). Ein sprengkräftiger Prüfzünder Nr. 1 mit 0,25 g PETN diente als Referenz. Zur Nachweisführung kam der Stahlplattendurchschlag als etablierte Methode zur Unterscheidung zwischen Detonation und Deflagration zum Einsatz. Der Referenzversuch bestätigte erwartungsgemäß eine vollständige Detonation des NSP711. In keinem der insgesamt zehn Versuche mit den untersuchten pyrotechnischen Gegenständen konnte hingegen eine Initiierung des Sekundärsprengstoffs nachgewiesen werden. Es traten weder Durchschläge noch Verformungen der Nachweisplatten auf; stattdessen fand sich nicht detonierter Sprengstoff verteilt im Versuchsumfeld. Zusammenfassend belegen die Ergebnisse, dass die geprüften pyrotechnischen Gegenstände der Kategorie P1 nicht in der Lage sind, den Sekundärsprengstoff NSP711 zu initiieren. Damit wurde die Erfüllung der ESR 4 b) der Richtlinie 2013/29/EU für die untersuchten Anzünder nachgewiesen. Die Ergebnisse lassen sich zudem auf pyrotechnische Gegenstände mit vergleichbarem oder geringerem energetischem Potenzial übertragen und direkt auf die Konformitätsbewertung im Sinne einer Effizienzsteigerung und Kostenreduktion anwenden.
The Data Exchange in the Process Industry (DEXPI) standardization group has recently released a new specification addressing early process design information, particularly information found in block flow diagrams (BFDs) and process flow diagrams (PFDs). The specification provides an information model and exchange format for such design information, but it does not yet define a graphical notation or modeling approach for creating and exchanging compliant BFDs or PFDs. Our work investigates the structural and semantic correspondence between the DEXPI Process information model and the Business Process Model and Notation 2.0 (BPMN 2.0) standard and proposes a BPMN 2.0-based representation for DEXPI’s BFDs and PFDs. The approach is validated using the Tennessee Eastman process as a case study. The results show that BPMN 2.0 can represent and exchange DEXPI Process-relevant design information in a semantic and standardized way, that the resulting models can be transformed into schema-valid DEXPI 2.0 XML, and that it provides a practical and tool-supported basis for graphical modeling of BFDs and PFDs. To support adoption, we provide an open-source reference implementation, bpmn2dexpi, that realizes the proposed representation, transforms BPMN 2.0 models into DEXPI 2.0-compliant XML, and validates the output against the DEXPI 2.0 XML Schema and information model.
With growing interest in electrochemical processes in supporting a future low-carbon energy and chemical manufacturing infrastructure, modeling studies have surged. To provide structure to the expanding body of work, we present a review of the major electrolysis technologies and their modeling trends. Modeling efforts across the technologies are largely siloed, with each community employing different approaches and levels of rigor for varying modeling objectives. While the differences stem partly from the distinct phenomena involved, they are also due to limited exchange within a broader community. By comparing modeling practices for specific goals, e.g., models for design, operation, or start-up, we identify research gaps and opportunities for shared learning. Focusing on water electrolysis as well as the chlor-alkali process, we assess which practices should be continued, improved, or adopted to ultimately improve the fidelity and predictive capability of electrolytic process models.
