WELSIM has released the 2025R1, supporting molecular dynamics analysis

 

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The general engineering simulation software WELSIM has released the latest 2025R1 version (internal version 3.0). Compared to the previous version, the 2025R1 version includes many new features and enhancements, providing better support for various types of engineering simulation CAE analyses, especially with the addition of molecular dynamics analysis capabilities.

Support for the Molecular Dynamics Solver LAMMPS

The new version adds pre- and post-processing modules for the LAMMPS solver. Users can quickly generate the input scripts required for LAMMPS computation and can also directly call LAMMPS program through WELSIM for solving.

Currently, 36 commands are supported, covering approximately 36% of all LAMMPS commands, and all of these are core commands, which can meet the needs of general analyses.

In the pre-processing module, a molecular dynamics project option has been added, along with various conditions such as particle neighbor conditions, particle velocity, particle acceleration, initial displacement, boundary walls, force fields, etc. These pre-processing objects and properties are intuitive and easy to use.

The solving feature is consistent with the finite element solving method. During the computation, the solver’s output information is displayed in a pop-up window, allowing users to monitor the calculation status.

In terms of post-processing, WELSIM also supports some molecular dynamics-related features. It can read the log file (log.lammps) and result files (dump.lmps) generated by LAMMPS solver and display the results. The newly added particle display module can efficiently render particle trajectories and colors.

Enhancements and Upgrades

Additionally, the new version includes other new features and improvements. It supports the 3DConnexion 3D space mouse hardware and the export of result files in TecPlot format. It also adds atomic mass units and basic atomic materials such as H, He, Li, Be, B, C, N, O, F, Ne, and Na.

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WELSIM and the author are not affiliated with LAMMPS, TecPlot, or 3DConnexion. The use of LAMMPS, TecPlot, and 3DConnexion is for reference in this technical blog post and software usage only.

WELSIM发布2025R1版本，支持分子动力学计算

通用工程仿真分析软件WELSIM发布了最新的2025R1版本（内部版本号3.0）。相对于上一个版本，2025R1版本含有许多新的功能与增强，能够更好地支持各种类型的工程仿真CAE分析，尤其是增加分子动力学分析计算功能。

新增支持开源求解器LAMMPS

新版本增加了LAMMPS求解器的前后处理模块，用户可以快速的生成LAMMPS计算所需的输入文件，也可以直接通过WELSIM调用LAMMPS进行求解。

目前已经支持了36个命令，占LAMMP全部命令的36%左右，且全部为核心命令，能满足常用的分析。

在前处理功能上，增加了分子动力学项目，和各种条件，如粒子关系条件，粒子速度，粒子加速度，初始位移，边界墙，力场定义等等。这些前处理节点和属性，直观且易于使用。

求解功能和有限元计算方式一致，计算时，会在弹出窗口中现实求解器的输出信息，便于用户了解计算状态。

在后处理方面，WELSIM也已经支持了部分分子动力学相关的功能。可以读取LAMMPS计算生成的log文件log.lammps，以及计算结果文件dump.lmps。并显示计算结果。新增的粒子显示模块，可以高效率的渲染粒子的轨迹变化与颜色。

其他增强与升级

此外，新版本还有其他新功能与提升。如支持3DConnexion的三维空间鼠标硬件，支持导出TecPlot格式的结果文件。此外还增加了原子质量单位，增加了基础原子材料如H, He, Li, Be, B, C, N, O, F, Ne, Na。

WelSim与作者不隶属于LAMMPS, TecPlot, 3DConnexion。和以上开发团队与机构没有关系。这里引用LAMMPS，TecPlot和3DConnexion 仅用作技术博客文章与软件使用的参考。

Use WELSIM to generate LAMMPS solver input scripts

 LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) is an excellent general-purpose molecular dynamics open-source computational software, based on the GPL license. It is primarily used to simulate systems of atoms, molecules, and macroscopic particles and can run on both Windows and Linux operating systems. It was developed by the Sandia National Laboratories and is suitable for research in various fields, ranging from materials science to biophysics. The solver supports a rich set of force fields, many atomic types, excellent computational performance, parallel and GPU computing support, and can calculate various complex microscopic models. LAMMPS is widely used in academia and industry. The latest version is 2024August29, and the project team has made the full code open-source, while also providing compiled executables and numerous examples.

The LAMMPS solver input script format is simple and clear, similar to most finite element analysis solver formats, making it easy to learn. The file extension can be arbitrary, but *.in is commonly used. The input file controls various parameters, including analysis type, computing region, force fields, boundary conditions, and initial conditions. Additionally, the input script can read external files, such as a separate molecular data file. This is similar to finite element input script, where large mesh files are separated and read independently. The difference is that LAMMPS’ molecular files contain information like atomic coordinates, masses, molecular bonds, bounding boxes, etc.

To better support the open-source solver and simulation community, WELSIM has recently added support for LAMMPS pre- and post-processing. Users can quickly generate LAMMPS input files for simulations. After defining the model, users can select “Output LAMMPS Files” from the Tools menu to generate solver files in a specified directory.

After a successful export, a solver input file named lammps_welsim.in will be generated, which can directly be used for molecular dynamics simulations.

At the same time, WELSIM can directly call LAMMPS executable program to solve the generated scripts. After downloading the LAMMPS solver, users can configure the solver executable path (lmp.exe) via Preferences — Solver — LAMMPS executable file. After defining the model, users can solve the problem and obtain result files.

Since LAMMPS is the default molecular dynamics solver, there is no need to set the solver properties in the Study Settings when performing joint solving.

Supported Commands

The latest version of LAMMPS includes nearly 100 general commands, and WELSIM has currently supported 36 commands, which account for 36% of the total, all of which are core commands and meet most common analysis needs. The supported commands are as follows:

atom_modify, atom_style, boundary, comm_modify, comm_style, compute, compute_modify, create_atoms, create_bonds, create_box, dimension, displace_atoms, dump, dump_modify, echo, fix, group, include, lattice, log, mass, neigh_modify, neighbor, newton, pair_coeff, pair_modify, pair_style, region, run, special_bonds, thermo, thermo_modify, thermo_style, timestep, units, velocity.

More solver commands will be added with version updates and user needs.

Post-Processing of Molecular Dynamics Results

Currently, WELSIM supports some post-processing features related to molecular dynamics. It can read LAMMPS-generated log files (log.lammps) and result files (dump.lmps), and display the results in contour.

Conclusion

This blog introduces how to generate LAMMPS input scripts using WELSIM and how to set up joint solving. Thanks to its excellent GUI, users can quickly generate high-quality LAMMPS input scripts.

LAMMPS is licensed under the GPL open-source protocol, and WELSIM’s installation package does not include the LAMMPS solver. Users need to download the solver separately. With simple configuration, WELSIM can work together with LAMMPS to solve particle problems.

The LAMMPS input file functionality is available in the 2025R1 development version and will continue to be maintained and enhanced in the official and future releases.

WELSIM and the author are not affiliated with LAMMPS and have no connection with the LAMMPS development team or institutions. LAMMPS is referenced here solely for the purpose of this technical blog post and software usage.

使用WELSIM生成LAMMPS求解器输入文件

LAMMPS（Large-scale Atomic/Molecular Massively Parallel Simulator）是一款优秀的通用分子动力学开源计算软件，基于GPL协议，主要用于模拟原子、分子和宏观颗粒的系统，可以在Windows和Linux操作系统上运行。它由美国Sandia国家实验室开发，适用于从材料科学到生物物理等多个领域的研究。求解器支持丰富的力场，多种原子类型，优秀的求解性能，支持并行和GPU计算等，可计算各种复杂的微观模型。LAMMPS已经广泛用于学术与工业界。目前最新的版本是2024August29，项目方开源了全部代码，同时提供了编译后的可执行程序和大量实例。

LAMMPS求解器输入文件格式简洁明了，和大多数有限元计算格式相似，易于学习。文件后缀名可以任意，但常使用*.in。控制输入文件，含有分析类型，计算区域，力场，边界条件，初始条件等信息。同时，输入文件可以读取外部其他文件，如读取单独的分子数据文件。这和有限元文件输入文件类似，将数据量较大的网格文件独立出来单独读写。不同的是，Lammps的分子文件中包含的是原子坐标，质量，分子键，bounding box等信息。

为了更好的支持开源求解器与仿真社区，WELSIM近期支持了LAMMPS的前后处理，用户可以快速的生成LAMMPS计算所需的输入文件。用户在定义完模型后，在菜单栏的工具（Tools）选项中，选择输出LAMMPS文件，即可在指定目录得到求解器文件。

导出成功后，会生成一个名为http://lammps_welsim.in的求解器输入文件，可以直接用于分子动力学的求解计算。

同时，WELSIM可以直接调用LAMMPS进行计算。当下载LAMMPS求解器文件后，可以通过首选项 – 求解器 - LAMMPS可执行文件，来配置求解器lmp.exe的路径。定义好模型后，可以直接求解，并得到结果文件。

由于LAMMPS是默认的分子动力学求解器，当进行联合求解时，无需将分析设置节点（Study Settings）的求解器属性设定为LAMMPS。

已经支持的命令

最新版的LAMMPS共有近100个通用命令，目前WELSIM已经支持了36个命令，占全部命令的36%，且全部为核心命令，已经满足常用的分析。支持的命令如下。

控制命令：atom_modify, atom_style, boundary, comm_modify, comm_style, compute, compute_modify, create_atoms, create_bonds, create_box, dimension, displace_atoms, dump, dump_modify, echo, fix, group, include, lattice, log, mass, neigh_modify, neighbor, newton, pair_coeff, pair_modify, pair_style, region, run, special_bonds, thermo, thermo_modify, thermo_style, timestep, units, velocity

更多的求解器命令会随着版本迭代和用户需求，不断增加。

计算结果后处理

目前，WELSIM已经支持了部分分子动力学相关的后处理功能。可以读取LAMMPS计算生成的log文件log.lammps，和结果文件dump.lmps。并以云图显示计算结果。

总结

本文介绍了使用WELSIM生成LAMMPS计算文件，和联合求解的设置。得益于优异的GUI，用户可以快速生成高质量的LAMMPS输入文件。

LAMMPS使用GPL开源协议，WELSIM的安装包中不含LAMMPS求解器。用户需要自行下载求解器。通过简单配置，即可使用WELSIM与LAMMPS联合求解工程问题。

LAMMPS输入文件的功能已经在2025R1开发版中，会在正式版和以后的版本中不断维护与增强。其他开源求解器的支持，可以参考《使用WELSIM生成SU2求解器文件》，《使用WELSIM调用OpenRadioss进行显示动力学分析》，《使用WelSim生成FrontISTR网格与输入文件》，《使用WELSIM生成MFEM初始网格文件》，《使用WELSIM生成电磁计算软件Palace的求解器文件》, 《使用WELSIM生成Elmer FEM求解器输入文件》。

WelSim与作者不隶属于LAMMPS。和LAMMPS开发团队与机构没有直接关系。这里引用LAMMPS仅用作技术博客文章与软件使用的参考。