Agus L. Soenjaya

a.soenjaya@unsw.edu.au

Postdoctoral Researcher

School of Mathematics and Statistics

UNSW Sydney

About me

Hi! I'm Agus, a postdoctoral researcher in the department of Applied Mathematics at UNSW Sydney. I recently graduated with a PhD in Applied Mathematics from UNSW, supervised by Prof. Thanh Tran (UNSW) and Prof. Ben Goldys (University of Sydney).

I will begin a postdoctoral research position at the Institute of Analysis and Scientific Computing, TU Wien in July 2026.

My PhD research studies well-posedness and numerical approximations of various deterministic and stochastic PDEs arising in micromagnetics at elevated temperatures. My PhD thesis can be found here.

Research interests

My research explores how complex physical systems, from the mixtures of fluids to the behaviour of conducting plasmas, evolve over time. These processes are often described by partial differential equations (PDEs). In many cases, they are influenced by random effects, such as thermal fluctuations or microscopic noise. To capture this uncertainty, I work with stochastic PDEs (SPDEs), which combine the laws of physics with randomness. Nonlinearity is an important theme in my work.

My research focuses on developing and analysing stable and structure-preserving finite element methods: computational methods that not only approximate solutions to PDEs or SPDEs accurately but also respect the underlying physical laws, such as conservation of energy or mass. This allows simulations to remain faithful to the true behaviour of the system.

Currently, I am particularly interested in the Cahn–Hilliard-type equations (modelling phase separation in materials and tumour growth), the Landau–Lifshitz–Gilbert and Landau–Lifshitz–Bloch equations (describing magnetisation dynamics), and the magnetohydrodynamics (MHD) equations (governing interaction between plasmas and magnetic fields).

Recent publications

Some recent publications are listed here. A complete list can be found under the 'CV' tab. Click on the link to access the paper.

Strong convergence of finite element schemes for the stochastic Landau–Lifshitz–Bloch equation. IMA J. Numerical Analysis (2026, to appear). arXiv:2602.18021.
Error analysis of scalar auxiliary variable finite element methods for the Landau–Lifshitz–Bloch equation. Computers and Mathematics with Applications, 217 (2026).
Numerical analysis of the Landau-Lifshitz-Bloch equation with spin-torques. ESAIM: Mathematical Modelling and Numerical Analysis, 60, no. 3 (2026)
(with B. Goldys and T. Tran) A mixed finite element method for a class of fourth-order stochastic evolution equations with multiplicative noise. ESAIM: Mathematical Modelling and Numerical Analysis, 60, no. 2 (2026)
(with K. Le and T. Tran) The Landau-Lifshitz-Bloch equation in polytopal domains: Unique existence and finite element approximation. IMA J. Numerical Analysis (2026), drag002.

Recent preprints

Some recent preprints are listed here. A complete list can be found under the 'CV' tab. Click on the link to access the preprint (or send me an e-mail if no link is available yet!).

A priori error analysis of a mass-lumped midpoint finite element method with a structure-preserving solver for the Landau–Lifshitz–Gilbert equation with Dzyaloshinskii–Moriya interaction. arXiv:2606.16142 (2026).
(with B. Goldys and T. Tran) Error analysis of a divergence-preserving mixed finite element scheme for the incompressible Hall-magnetohydrodynamic equation. arXiv:2605.01764 (2026).
(with P. Lin and T. Tran) Error analysis of a fully discrete structure-preserving finite element scheme for a diffuse-interface model of tumour growth. arXiv:2509.14486 (2025).

Work in progress

Some work in progress - these will be completed soon!

Structure-preserving finite element scheme for the Landau–Lifshitz–Bloch equation at any temperatures (2026).

NEWS:

20 May 2026: My PhD degree is officially approved by the faculty! My PhD thesis can be found here. I will begin a postdoctoral research position at the Institute of Analysis and Scientific Computing, TU Wien in July 2026.
6 March 2026: I have finally submitted my PhD thesis for examination!
9 December 2025: I'm presenting at the Computational Mathematics and Stochastic Differential Equations special sessions of the AustMS Meeting 2025 at La Trobe University.
22 September 2025: I'm attending a special topic school on Optimality of adaptive finite element methods organised by the Hausdorff School for Mathematics at the University of Bonn. I'm also visiting Prof. Michael Feischl at TU Wien to work on a project related to structure-preserving FEM for the fully nonlinear Landau-Lifshitz-Bloch equation.
24 June 2025: I'm presenting at the 30th Biennial Numerical Analysis Conference organised by the University of Strathclyde, Glasgow. My talk will be on Finite element approximations of a micromagnetic model at elevated temperatures. The slides can be found here.
I'm also visiting Prof. Ping Lin at the University of Dundee to complete a project on structure-preserving FEM for a diffuse-interface model of tumour growth.

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