arXiv subjects

Pawan Kumar Pandey

Publications and source records attributed to Pawan Kumar Pandey.

4 recordsLinked to original sources

arXiv2026

Effects of Porous Media Properties and Flow Environment on Drug Release from Porous Implants

Drug-Filled Porous Implants (DFPIs) are an innovative solution for delivering drugs in a controlled and sustained manner to target sites. To optimize their performance across various physiological conditions, it is essential to understand how fluid flow and porous media properties influence the drug release process. In this work, we numerically investigate a wide range of flow conditions and their effects on drug release from DFPI. The DFPI is modeled as a homogeneous, saturated porous medium, with flow through the porous structure modeled using the Forchheimer-extended Darcy law. Drug diffusion within the DFPI and its transport through the surrounding channel are simulated using a diluted species transport approach. The results reveal the impact of flow conditions and porous media characteristics on the drug release profile of the implant and drug availability within the channel. The variations in drug release behavior are analyzed by modeling the release as an apparent first-order process with a time-dependent rate constant. Notably, the results highlight specific conditions under which the rate constant increases during the later stages of drug release from the DFPI, particularly at high Reynolds numbers, while also ensuring a prolonged operational time period of the implant. These findings suggest the potential for developing intelligent DFPI designs capable of delivering drugs in a manner more attuned to the specific needs of the application.

physics.chem-ph↗

arXiv2021

Quantifying the Consequences of Catheter Steerability Limitations on Targeted Drug Delivery

In this work, we virtually study the intra-arterial targeted drug delivery. Specifically, this work models and quantifies the uncertainties associated with catheter steerability limitations. We classify catheter's limited steerability into two types, i.e., zero steerability, and wall pressing steerability. Further, we investigate the effects of steerability limitations on uncertainty of causing systemic toxicity levels, i.e., percentage of drug particles missing target. Proposed method quantifies the uncertainty of causing systemic toxicity in terms of probability. With this calculation approach, we look at the effects of upstream vasculature and catheter tip size. Results indicate the existence of a 'transition toxicity' level. Beyond transition toxicity level, larger catheters should be preferred over smaller catheters. Furthermore, we found that it is relatively easier to decide preferrable catheter size in zero-steerability than wall-pressing steerability conditions.

physics.med-ph↗

arXiv2021

Effect of Foam Insertion in Aneurysm Sac on Flow Structures in Parent Lumen: Relating Vortex Structures with Disturbed Shear

Numerous studies suggest that disturbed shear, causing endothelium dysfunction, can be related to neighboring vortex structures. With this motivation, this study presents a methodology to characterize the vortex structures. Precisely, we use mapping and characterization of vortex structures' changes to relate it with the hemodynamic indicators of disturbed shear. Topological features of vortex core lines (VCLs) are used to quantify the changes in vortex structures. We use the Sujudi-Haimes algorithm to extract the VCLs from the flow simulation results. The idea of relating vortex structures with disturbed shear is demonstrated for cerebral arteries with aneurysms virtually treated by inserting foam in the sac. To get physiologically realistic flow fields, we simulate blood flow in two patient-specific geometries before and after foam insertion, with realistic velocity waveform imposed at the inlet, using the Carreau-Yashuda model to mimic the shear-thinning behavior. With homogenous porous medium assumption, flow through the foam is modeled using the Forcheimmer-Brinkmann extended Darcy model. Results show that foam insertion increases the number of VCLs in the parent lumen. The average length of VCL increases by 168.9% and 55.6% in both geometries. For both geometries under consideration, results demonstrate that the region with increased disturbed shear lies in the same arterial segment exhibiting an increase in the number of oblique VCLs. Based on the findings, we conjecture that an increase in oblique VCLs is related to increased disturbed shear at the neighboring portion of the arterial wall.

physics.flu-dyn↗

arXiv2021

Three Dimensional Simulation of Oscillatory Flow in Partial Porous Tube

Characteristics of Oscillating Flow in a Straight Tube with varying thickness of porous layer at the wall is studied. Results for two different porous layer is discussed and compared in terms of Velocity Profile, phase differences and radial position of maximum velocity over the cross-section. Present problem is modeled using Navier-Stokes Equation in clear medium at the core of tube while Darcy-BrinkmannForcheimmer Model is used for the outer porous layer. Solutions for these equations have been obtained using Finite Volume Method based 3D unstructured solver. Velocity profile obtained for tube with high permeability porous layer is the main highlight of results.

physics.flu-dyn↗