2DM File

What are 2DM files and how to open them

Are you having problems opening a 2DM file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your 2DM files.

What is a 2DM file?

A .2DM file is a SMS 2D Mesh file.

SMS 2D Mesh is a text-based file format used by Surface-Water Modeling System (SMS) to store two-dimensional unstructured mesh data. It holds the geometry of finite-element or finite-volume meshes: the locations of nodes, how elements (cells, triangles or quadrilaterals) connect those nodes, material type identifiers, boundary or node strings, and elevation (bathymetry) information. These files are produced when creating a 2D mesh for simulations of surface water flow, flood plains, rivers, or for coupling with numerical models like SRH-2D or TUFLOW. The main function of a .2dm mesh file is to serve as the mesh input that SMS or compatible modeling tools require to set up the domain before doing computations.

The program that writes .2dm files is SMS (Surface-Water Modeling System) by Aquaveo. In SMS the user designs a Generic 2D Mesh coverage in the MAP module, uses scatter or contour input to set elevations (if needed), defines elements (triangles, quadrilaterals, sometimes higher-order elements), assigns materials, boundary node strings, and other parameters, then saves the mesh as a .2dm file. Other modeling tools such as SRH-2D accept these .2dm files as input; in some workflows the mesh file may be edited or visualized separately, then loaded into SMS or another compatible tool for simulation or post-processing.

Files in this format begin with an ASCII card named MESH2D at the top. Subsequent lines use keywords such as ND (node definitions), E3T (triangular elements), E4Q (quadrilateral elements), NUM_MATERIALS_PER_ELEM (for material counts), NS or NODESTRING (for boundary or domain edges). The signature MESH2D appears at offset 0 (bytes "MESH2D") to indicate the start of such a file.

How to open 2DM files

Important: Different programs may use files with the 2DM file extension for different purposes, so unless you are sure which format your 2DM file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested two different 2DM openers which you will find listed below.

Last updated: August 16, 2026

Various apps that use files with this extension

These apps are known to open certain types of 2DM files. Remember, different programs may use 2DM files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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