Nektar1D:
A numerical code for solving the 1-D equations of blood flow in arterial networks
Nektar1D is our in-house computer code for solving the nonlinear, one-dimensional (1-D) equations of blood flow across a specified network of compliant vessels under prescribed boundary and initial conditions. It computes blood pressure, flow, and luminal area waveforms at any point within an arterial network, playing a crucial role in our research, as described here.
A reference manual for Nektar1D, including instructions for compiling the code, creating and running simulations, and interpreting results, is available for download. To request the necessary files for compiling Nektar1D on your computer along with sample simulations from our articles, please email jordi.alastruey-arimon@kcl.ac.uk.

For a comprehensive review of arterial pulse wave haemodynamics and a detailed derivation of the 1-D/0-D governing equations, see Am J Physiol, 2023, along with its Technical Supplement. Details on the numerical scheme used in Nektar1D are available in this book chapter.

Nektar1D has been verified against (i) experimental data in a 1:1 scale cardiovascular simulator rig of the aorta and large branches made of silicone tubes (J Biomech, 2011 & 2007), (ii) in vivo human (Heliyon, 2024; J Royal Soc Interface, 2016) and rabbit (J. Biomech, 2009) data, and (iii) numerical solutions from full 3-D blood flow equations in compliant vessels (J Royal Soc Interface, 2021 & 2016; Ann Biomed Eng, 2016; Int J Numer Meth Biomed Engng, 2014). The discontinous Galerkin scheme in Nektar1D was benchmarked against five other numerical schemes for 1-D blood flow modelling, showing good agreement among all numerical schemes (Int J Numer Meth Biomed Engng, 2015).

We have developed novel methods to calibrate 1-D/0-D pulse wave models and analyse the physical mechanisms in simulated pulse waveforms.

We have used Nektar1D to generate populations of thousands of virtual subjects for in silico evaluation of pulse wave indices and algorithms (Biomed Signal Process Control, 2024; Symmetry, 2021; Am J Physiol, 2019 and 2015; J Biomech, 2016) and has been applied in clinically relevant studies, as described here.

Recently, Nektar1D was coupled to a 3-D cardiac electromechanics model, enabling studies on the effects of pulse wave propagation on cardiac function (Comput Mech, 2022).