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 AdditiveFOAM is a framework for simulating transport phenomena relevant to Additive Manufacturing (AM) processes that is built on OpenFOAM [@openfoam], the leading free, open-source software package for computational fluid dynamics (CFD). OpenFOAM provides a comprehensive suite of tools that leverage state-of-the-art finite volume methods in an extensible framework for solving complex multiphysics problems. AdditiveFOAM leverages these capabilities to incorporate specialized tools tailored to addressing AM processing challenges.
 
-Metal additive manufacturing, also known as metal 3D printing, is an advanced manufacturing technique used for creating physical parts from a three-dimensional (3D) digital model via selectively melting metal powder or wire feedstock. An active area of research in metal AM is focused on process planning to mitigate anomalous features during printing that are deleterious to part performance (e.g. porosity and cracking) as well as localized microstructure and material properties control. Comprehensive experimental campaigns to qualify new materials, processes, and parameter spaces are time-consuming and costly, motivating researchers to deploy advanced numerical models.
+Metal additive manufacturing, also known as metal 3D printing, is an advanced manufacturing technique used for creating physical parts from a three-dimensional (3D) digital model via melting metal powder or wire feedstock. An active area of research in metal AM is focused on process planning to mitigate anomalous features during printing that are deleterious to part performance (e.g. porosity and cracking) as well as localized microstructure and material properties control. Comprehensive experimental campaigns to qualify new materials, processes, and parameter spaces are time-consuming and costly, motivating researchers to deploy advanced numerical models.
 
 # Statement of need
 
-Numerical models for AM traditionally generally seek to represent physics at a single length scale depending on the target question. Two main categories of models with available software solutions are distinguished: 1) high-fidelity melt pool-scale models, and 2) part-scale heat transfer models. 
+Numerical models for AM traditionally seek to represent physics at a single length scale depending on the target question. Two main categories of models with available software solutions are distinguished: 1) high-fidelity melt pool-scale models, and 2) part-scale heat transfer models. 
 
-The first category contains models which seek to resolve all relevant physics within the melt pool. These models can produce excellent agreement with experiments and offer insights into the underlying causes of anomalous features during processing, but are generally expensive to run, limiting the scan length that can be simulated to a few millimeters with current computational resources. Due to their computational expense, these models are well-suited for use at specialized research institutions with large HPC infrastructure to answer target questions about melt pool scale physical phenomena. An exhaustive list of high-fidelity melt pool models is beyond the current scope; however, two primary software packages are highlighted: 
+The first category contains models which seek to resolve all relevant physics within the melt pool. These models can produce excellent agreement with experiments and offer insights into the underlying causes of anomalous features during processing, but are generally expensive to run, limiting the scan length that can be simulated to a few millimeters with current computational resources. Due to their computational expense, these models are well-suited for use at specialized research institutions with large HPC infrastructure to answer target questions about melt pool scale physical phenomena. An exhaustive review of high-fidelity melt pool models is beyond the current scope of this article; however, two primary software packages are highlighted: 
 
 - ALE3D [@ALE3D] is a versatile multiphysics simulation tool that uses the Arbitrary Lagrangian-Eulerian approach and has been used for powder-resolved simulations of laser-material interactions in AM. However, ALE3D is a limited access code for use by DoD and DOE laboratories and their contractors and ALE3D4I is available for U.S. companies and academics through individual use agreements. 
 
@@ -56,7 +56,7 @@ There is an established need for intermediate frameworks that are capable of acc
 These software tools are promising platforms for further development of GPU-capable mesoscale simulations of AM processes, however at present, they remain limited to single gaussian heat sources and do not consider fluid flow or general thermodynamic pathways which may be important for accurate predictions of the conditions that lead to anomalous features and microstructure evolution during printing. 
 
 # Software Features
-AdditiveFOAM features a volumetric heat source library that supports any number of independently moving sources with distinct energy profiles that have been validated for a number of AM processes. The volumetric source term is used in the solution of the unsteady, nonlinear heat equation which considers three distinct phases (solid, liquid, and powder) as a continuum. A novel thermodynamic algorithm enables variable-order time integration for any thermodynamic pathway supported through tabulated solid fraction-temperature lookup tables. The available time integration schemes are explicit forward Euler, implicit backward Euler, Backward differentiation formula (BDF-2), and Crank-Nicolson. An adaptive time integration can be enabled along with adaptive time integration to balance the computational cost and solution accuracy depending on the problem state. Additionally, AdditiveFOAM features boundary conditions for Marangoni driven fluid flow in the melt pool as well as convective and radiative heat transfer. Finally, AdditiveFOAM leverages existing OpenFOAM libraries to sample thermal data needed for microstructure predictions with a specific library for coupling to the grain structure prediction software ExaCA [@exaca]. 
+AdditiveFOAM features a volumetric heat source library that supports any number of independently moving sources with distinct energy profiles that have been validated for a number of AM processes. The volumetric source term is used in the solution of the unsteady, nonlinear heat equation which considers three distinct phases (solid, liquid, and powder) as a continuum. A novel thermodynamic algorithm enables variable-order time integration for any thermodynamic pathway supported through tabulated solid fraction-temperature lookup tables. The available time integration schemes are explicit forward Euler, implicit backward Euler, Backward differentiation formula (BDF-2), and Crank-Nicolson. An adaptive time integration and time stepping method automatically switches between implicit and explicit schemes to balances the computational cost and solution accuracy depending on the problem state and user defined tolerances. Additionally, AdditiveFOAM features boundary conditions for Marangoni driven fluid flow in the melt pool as well as convective and radiative heat transfer. Finally, AdditiveFOAM leverages existing OpenFOAM libraries to sample thermal data needed for microstructure predictions with a specific library for coupling to the grain structure prediction software ExaCA [@exaca]. Future releases of AdditiveFOAM will focus on resource-optimized adaptive mesh refinement (AMR) as well as dynamic load-balancing using the Zoltan [@zoltan] library.
 
 AdditiveFOAM was designed to be used openly by researchers, industry, and academics. It has already been used in a number of scientific publications primarily focused on studying how AM process planning influences the development of local microstructural features in a part. Select publications that demonstrates AdditiveFOAM’s usage towards understanding the connection between process planning and microstructure evolution in metal AM include: