Kartik Jain

• Dr.-Ing.
• Professor (Assistant) at University of Twente

Many complications in physiology are associated with a deviation in flow in arteries due to a stenosis. The presence of stenosis may transition the flow to weak turbulence. The degree of stenosis as well as its configuration whether symmetric or non-symmetric to the parent artery influences whether the flow would stay laminar or transition to turbu...

Flows through medical devices as well as in anatomical vessels despite being at moderate Reynolds number may exhibit transitional or even turbulent character. In order to validate numerical methods and codes used for biomedical flow computations, the US Food and Drug Administration (FDA) established an experimental benchmark, which was a pipe with...

Onset of flow transition in a sinusoidally oscillating flow through a rigid, constant area circular pipe with a smooth sinusoidal obstruction in the center of the pipe is studied by performing direct numerical simulations, with resolutions close to the Kolmogorov microscales. The studied pipe is stenosed in the center with a 75% reduction in area i...

The phase 3 of the cerebral aneurysm detection and analysis (CADA) challenge involved rupture risk estimation of intracranial aneurysms using computational methods. In this work we performed computational fluid dynamics (CFD) on a subset of aneurysm cases provided by the challenge committee. A large number of aneurysm cases were available, CFD anal...

Numerical simulations are widely used to study the behavior of suspension flows. Fully resolved simulations, in which the detailed flow around individual particles is computed, are accurate but computationally expensive. Unresolved methods reduce the computational cost significantly by only resolving the bulk flow and modeling the small-scale flow...

Many interesting particulate flow problems can only be studied using efficient numerical methods. We present a method based on a lattice Boltzmann fluid coupled to unresolved particles that interact with each other via the Discrete Element Method. Our method improves upon existing numerical schemes through the addition of a novel subcycling algorit...

Ultrasound contrast agents have been used as vascular reporters for the past 40 years. The ability to enhance vascular features in ultrasound images with engineered lipid-shelled microbubbles has enabled break-throughs such as the detection of tissue perfusion or super-resolution imaging of the microvasculature. However, advances in the field of co...

Purpose In arterial disease, the presence of two or more serial stenotic lesions is common. For mild lesions, it is difficult to predict whether their combined effect is hemodynamically significant. This study assessed the hemodynamic significance of idealized serial stenotic lesions by simulating their hemodynamic interaction in a computational fl...

Purpose] Transarterial radioembolization (TARE) is an established treatment modality for patients with unresectable liver cancer. However, a better understanding of treatment parameters that influence microsphere distribution could further improve the therapy. This systematic review examines and summarizes the available evidence on intraprocedural...

Fibrotic tumors, such as pancreatic ductal adenocarcinoma (PDAC), are characterized for high desmoplastic reaction, which results in high intra-tumoral solid stress leading to the compression of blood vessels. These microarchitectural alterations cause loss of blood flow and poor intra-tumoral delivery of therapeutics. Currently, there is a lack of...

There is a considerable interest in understanding transient human upper airway aerodynamics, especially in view of assessing the effects of various ventilation therapies. Experimental analyses in a patient-specific manner pose challenges as the upper airway consists of a narrow confined region with complex anatomy. Pressure measurements are feasibl...

The dynamics of particle transport in a flow are important to understand many complex physio-logic phenomena like the trajectories of microspheres in liver vasculature during a radioembolization procedure. We developed a framework capable of simulating fully resolved particles in complex ge-ometries using the Lattice Boltzmann method and the moment...

Many complications in physiology are associated with a deviation in flow in arteries due to a stenosis. The presence of stenosis may transition the flow to weak turbulence. The degree of stenosis as well as its configuration whether symmetric or non-symmetric to the parent artery influences whether the flow would stay laminar or transition to turbu...

The Cerebral Aneurysm Detection and Analysis (CADA) challenge was organized to support the development and benchmarking of algorithms for detecting, analyzing, and risk assessment of cerebral aneurysms in X-ray rotational angiography (3DRA) images. 109 anonymized 3DRA datasets were provided for training, and 22 additional datasets were used to test...

The assessment of local blood flow patterns in patients with peripheral arterial disease is clinically relevant, since these patterns are related to atherosclerotic disease progression and loss of patency in stents placed in peripheral arteries, through mechanisms such as recirculating flow and low wall shear stress (WSS). However, imaging of vascu...

The intrinsic permeability is a crucial parameter to characterise and quantify fluid flow through porous media. However, this parameter is typically uncertain, even if the geometry of the pore structure is available. In this paper, we perform a comparative study of experimental, semi-analytical and numerical methods to calculate the permeability of...

Flows through medical devices as well as in anatomical vessels despite being at moderate Reynolds number may exhibit transitional or even turbulent character. In order to validate numerical methods and codes used for biomedical flow computations, the U.S. food and drug administration (FDA) established an experimental benchmark, which was a pipe wit...

The movement of cerebrospinal fluid (CSF) is linked to the cardiovascular and respiratory systems. The heart not only drives blood flow but is also at the origin of CSF pulsation through the expansion and contraction of cerebral blood vessels. Respiration modulates this cardiovascular action while also directly influencing spinal subarachnoid space...

Purpose Image-based computational fluid dynamics (CFD) is widely used to predict intracranial aneurysm wall shear stress (WSS), particularly with the goal of improving rupture risk assessment. Nevertheless, concern has been expressed over the variability of predicted WSS and inconsistent associations with rupture. Previous challenges, and studies f...

The onset of transitional flow in cerebral aneurysms has previously been demonstrated in numerical simulations but it remains to be seen if this phenomenon is present in vivo as the detection of such flow fluctuations is difficult with the resolution of modern imaging. Here, we experimentally investigate the presence of transitional flow in physica...

Obstruction to the cerebrospinal fluid (CSF) outflow caused by the herniation of cerebellar tonsils as a result of Chiari malformation type I leads to altered CSF hydrodynamics. This contribution explores the minutest characteristics of the CSF hydrodynamics in cervical subarachnoid spaces (SAS) of a healthy subject and two Chiari patients by perfo...

The advent of supercomputers has made it possible to simulate physiological flows and improve understanding of pathology and pathophysiology of various diseases. Physiological flows, in spite of low Reynolds number (Re< 500), are known to exhibit turbulent like activity. This thesis investigates the onset of flow-transition in blood flow in intracr...

This contribution presents the performance of the Lattice Boltzmann implementation Musubi on four different High Performance Computing architectures. Musubi is maintained within the APES simulation framework that makes use of a distributed octree mesh representation and includes a mesh generation and a postprocessing tool to enable end-to-end paral...

The present contribution reports direct numerical simulations of pulsatile flow through a 75% eccentric stenosis using the Lattice Boltzmann Method (LBM). The stenosis was previously studied by Varghese, Frankel, and Fischer in a benchmark computation, and the goal of this work is to evaluate the LBM and the solver Musubi for transitional flows in...

The present contribution reports direct numerical simulations of pulsatile flow through a 75% eccentric stenosis using the Lattice Boltzmann Method (LBM). The stenosis was previously studied by Varghese, Frankel, and Fischer in a benchmark computation, and the goal of this work is to evaluate the LBM and the solver Musubi for transitional flows in...

The present contribution reports direct numerical simulations of pulsatile flow through a 75% eccentric stenosis using the Lattice Boltzmann Method (LBM). The stenosis was previously studied by Varghese, Frankel, and Fischer in a benchmark computation, and the goal of this work is to evaluate the LBM and the solver Musubi for transitional flows in...

High fidelity Lattice Boltzmann method based direct numerical simulations were conducted on 12 intracranial aneurysms previously studied in order to explore the critical Reynolds number at which the flow regime transitions from laminar to the one that exhibit high frequency fluctuations in aneurysms. The outcomes of an in-depth space-time refinemen...

Simulations at extreme scale generate large amounts of data. As sufficiently large resources to handle the large data sets are generally available only in a distributed form, the complete tool chain deployed to obtain simulation results needs to be usable on distributed systems. In this work we present the APES framework which provides such a tool...

Electrodialysis is an energy efficient sea water desalination technique. It uses selective ion exchange membranes to remove salt ions from sea water under the influence of an applied external electrical field. In the electrodialysis module, a complex structure referred to as spacer is used in the channels to keep the membranes apart. This spacer in...

This paper considers a multiscale description of thrombus formation and its simplified numerical implementation in the case of cerebral aneurysms. In particular, we extend previously introduced generic 2D models towards 3D patient specific aneurysm geometries. The multiscale amplification method contributes to considerably reducing simulation time....

This contribution presents the results of numerical simulations of thrombosis in a patient specific cerebral aneurysm, deployed with stents of different porosity. The thrombosis models are based on low wall shear stress constraint and high residence time of fluid. Simulations have been performed with a massively parallel Lattice Boltzmann solver on...

The need for numerical simulation of fluid flows in highly complex geometries for medical or industrial applications has increased tremendously over the recent years. In this context the lattice Boltzmann method which is known to have a very good parallel performance is well suited. In this publication the lattice Boltzmann solver Musubi which is a...