GMeshNet-OSS-8B

GMeshNet-OSS-8B is an open-source, dense, decoder-only 8B parameter large language model optimized for chain-of-thought reasoning, designed to produce structured analyses and generate robust Gmsh meshing scripts.

---

Quickstart

Install Dependencies

pip install -U torch transformers accelerate

Run Inference

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer

# Input your prompt here
USER_INPUT = """
Generate a GMSH script to create a 2D rectangular mesh with a circular hole at the center, applying finer mesh refinement near the hole and coarser mesh at the boundaries.
"""

def load_model(model_path):
    model = AutoModelForCausalLM.from_pretrained(
        model_path,
        torch_dtype=torch.float16,
        device_map="auto",
        trust_remote_code=True
    )
    
    tokenizer = AutoTokenizer.from_pretrained(
        model_path,
        trust_remote_code=True
    )
    
    with open(f"{model_path}/chat_template.jinja", "r") as f:
        tokenizer.chat_template = f.read()
    
    return model, tokenizer

def generate_response(model, tokenizer, user_input):

    formatted_input = f"<gmsh_instruction>{user_input.strip()}</gmsh_instruction>"
    messages = [{"role": "user", "content": formatted_input}]
    
    prompt = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
    inputs = tokenizer(prompt, return_tensors="pt").to(model.device)
    
    outputs = model.generate(
        **inputs,
        max_new_tokens=2000,
        temperature=0.7,
        do_sample=True,
        pad_token_id=tokenizer.eos_token_id
    )
    
    response = tokenizer.decode(outputs[0], skip_special_tokens=False)
    return response.split("<|im_start|>assistant\n")[-1].replace("<|im_end|>", "").strip()

def run_inference():
    model_path = "./" # Path to your model weights
    
    model, tokenizer = load_model(model_path)
    result = generate_response(model, tokenizer, USER_INPUT)
    
    print(result)

if __name__ == "__main__":
    run_inference()

---

Example Output

<think>
I need to analyze this meshing task step by step to create an effective GMSH script.

1. Geometry Requirements:
   - Main domain: Rectangular plate (let's assume 10x10 units)
   - Internal feature: Circular hole at center (radius 1 unit)
   - Mesh requirements: Finer elements near hole, coarser elements at boundaries

2. Meshing Approach:
   - Unstructured triangular mesh for flexibility around complex features
   - Size field to control element gradation from fine near hole to coarse at boundaries
   - Boundary layer not strictly necessary but could be added if flow simulation is intended

3. Construction Steps:
   - Define rectangle points (4 corners)
   - Define circle points (center + 4 quadrant points)
   - Create line loops for both shapes
   - Create surface with hole using Plane Surface command
   - Set up size field for gradation control
   - Generate mesh
</think>
<response>
1. High-level overview:
   - Create 10x10 rectangular domain centered at origin
   - Add circular hole of radius 1 at center
   - Use distance-based size field to refine mesh near hole
   - Generate unstructured triangular mesh with smooth gradation

2. Step-by-step instructions:
   a) Create rectangle points (4 corners)
   b) Create circle points (center + 4 quadrants)
   c) Connect points with lines/arcs
   d) Form line loops
   e) Create surface with hole
   f) Set up size field
   g) Generate mesh

3. Complete GMSH script:

```
// Rectangle with circular hole - graded mesh example

// Geometry parameters
rect_size = 5;  // Half-width/height of rectangle
hole_radius = 1; // Radius of central hole

// Points for rectangle
Point(1) = {-rect_size, -rect_size, 0};
Point(2) = {rect_size, -rect_size, 0};
Point(3) = {rect_size, rect_size, 0};
Point(4) = {-rect_size, rect_size, 0};

// Points for circle (center + 4 quadrants)
Point(5) = {0, 0, 0}; // Center
Point(6) = {hole_radius, 0, 0};
Point(7) = {0, hole_radius, 0};
Point(8) = {-hole_radius, 0, 0};
Point(9) = {0, -hole_radius, 0};

// Lines for rectangle
Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 1};

// Circle arcs
Circle(5) = {6, 5, 7};
Circle(6) = {7, 5, 8};
Circle(7) = {8, 5, 9};
Circle(8) = {9, 5, 6};

// Line loops
Line Loop(1) = {1, 2, 3, 4}; // Outer rectangle
Line Loop(2) = {5, 6, 7, 8}; // Inner circle

// Surface with hole
Plane Surface(1) = {1, 2};

// Mesh size control - fine near hole, coarse at boundaries
Field[1] = Distance;
Field[1].NodesList = {5}; // Measure distance from center point
Field[1].NNodesByEdge = 100;

Field[2] = Threshold;
Field[2].InField = 1;
Field[2].SizeMin = 0.05; // Fine mesh near hole
Field[2].SizeMax = 0.5;  // Coarse mesh far away
Field[2].DistMin = hole_radius;
Field[2].DistMax = 2*hole_radius;

Background Field = 2;

// Physical groups for boundaries
Physical Curve("OuterBoundary", 1) = {1, 2, 3, 4};
Physical Curve("InnerBoundary", 2) = {5, 6, 7, 8};
Physical Surface("Domain", 1) = {1};

// Mesh settings
Mesh.Algorithm = 6; // Frontal-Delaunay
Mesh.Smoothing = 5;
Mesh.CharacteristicLengthExtendFromBoundary = 1;

// Generate 2D mesh
Mesh 2;
```

4. Implementation Notes:
   - To run: Open in GMSH → Mesh → 2D
   - Adjust parameters as needed:
     * rect_size: Change rectangle dimensions
     * hole_radius: Modify hole size
     * SizeMin/SizeMax: Control mesh density
     * DistMin/DistMax: Control refinement region extent
   - For structured mesh option, add Transfinite lines/surface commands
   - Visualize geometry first (Geometry tab) before meshing
   - Common errors to avoid:
     * Missing line loops
     * Incorrect point references in curves
     * Overlapping or intersecting geometries
</response>

---

Citation

@software{Callimesh_GMeshNet-OSS-8B_v1.0,
  author = {{Callimesh}},
  title = {GMeshNet-OSS-8B},
  version = {1.0.0},
  url = {https://huggingface.co/Callimesh/GMeshNet-OSS-8B},
  doi = {10.57967/hf/6325} 
}