# What is Mesh: Definition and 244 Discussions

A mesh is a barrier made of connected strands of metal, fiber, or other flexible or ductile materials. A mesh is similar to a web or a net in that it has many attached or woven strands.

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1. ### How can I fix the illegal data signal error in my FMESH tally code in MCNP6?

Hi everyone, I would help in such problem. i have tried to use a fresh card, but it always gives an illegal data signal am using mcnp6. here is my fmesh code. thanks FMESH44:n GEOM=X Y Z ORIGIN=-10 -10 -10 IMESH=-50 IINTS=5 JMESH=50 JINTS=11 KMESH=50 KINTS=8 EMESH= 1e-7...
2. ### Gmsh is crashing after change Extrude value from 10 to 100

Hello, here is my geo script of gmsh: (windows10 64bit) Point(1) = {0,-35,20}; Point(2) = {0,-35,-10}; Line(1) = {1, 2}; Point(3) = {0,35,-10}; Line(2) = {2, 3}; Point(4) = {0,35,20}; Line(3) = {3, 4}; Line(4) = {4, 4}; Point(5) = {0,0,0}; Line(5) = {4, 5}; Line(6) = {5, 1}; Line(7) = {1, 1}...
3. ### A K-point mesh and Monkhorst-Pack

Are the K-point mesh and monkhorst pack same. I was reading research papers using VASP and in some papers as the number of cells increases the Monkhorst Pack increases but in others the K-Point mesh decreases. Could some one clarify how these are used in the calculations.
4. ### I Circuits or edge-disjoint unions of circuits in a connected graph

Hi, I've a question related to the graph theory. Take a connected graph with ##n## nodes and ##b## edges. We know there are ##m = b - n + 1## fundamental circuits. Which is the total number of nonempty circuits or edge-disjoint unions of circuits ? If we do not take in account the circuit...
5. ### [ANSYS] Meshing based on Keypoints

I'm analyzing a longitudinal weld using the effective notch method to modell it. This means my mesh must be fine and more importantly very specific. To do this, I generated Keypoints where I want the nodes of the finite element mesh to be and this where I was stumped. I want to mesh it using...
6. ### Calculation of activation with mesh tally in MCNPX 2.6

Hi, All! Can anyone help me to construct a card for calculation of a spatial activation? Reaction is 27Al(n,p). I used a tmesh card for calculation of neutron flux as: tmesh rmesh21:n flux cora21 190 9i 210 corb21 -10 9i 10 corc21 -10 9i 10 ergsh21 0 20 endmd Somewhere in a problem I...
7. ### MCNP - FMESH vs. MESH cards

Hi everyone, I am struggling to understand the difference between FMESH and MESH. FMESH is used to create a mesh superimposed with the geometry but...what does MESH? Is it only involved in weight-window generation and not needed for mesh tallies? Thanks in advance for the clarification.
8. ### MCNP - z-coordinates of cylindrical mesh >0?

Hi everyone, I am using MCNP6.2 and trying to set up a cylindrical coordinate in a reactor channel. The origin as the midplane of the channel. In my attempt of setting up a cylindrical FMESH with the origin on the z-axis at the bottom of the channel (so z<0) I got this fatal error message...
9. ### Help with finding mesh currents and nodal analysis

Hi there, I have managed to work out the kirchoff's law bit but for the other two bits I just cant get started as I can get my head around it, its due in on monday I dont know why I left it so late!
10. ### A When should you use more mesh elements in the finite element method?

the simple rectangular isoparametric element (curved edges element) can be used to generate many complex shapes like.. square to circle square to triangle two square elements to annular. and the results i calculated in python code (2D case) are very accurate, then i confused why to use complex...
11. ### The stiffness of an FEA model depends on the mesh resolution?

As is well known, the stiffness of an FEA model decreases with a refined mesh. What's the rigorous derivation of this?
12. ### How to open an STL Mesh file in Linux

I am building up a mesh via defining a background mesh (using blockMesh) and snappyHexMesh I am dealing with the STL 2D Mesh surface (I cannot uploaded because PF doesn't accept zip files nor STL). My issue comes when I want to open it. When I run vi constant/triSurface/river.stl in the linux...
13. ### Airflow thru 6 mesh, .035 gauge screen

Happy Holidays! I saw your posting on airflow thru mesh screen and went to Perry's looking for answers. I haven't found what I'm looking for yet and was wondering if you can help? Our problem concerns bees coming down the chimney and how to stop them. We installed a Lymance chimney damper with...
14. ### Mesh change between FEA analysis types?

Hi all, Sorry of this is a silly question but it is one that recently came to mind and I cannot seem to find an answer to it: "should I change my mesh depending on the type of FEA analysis I am doing?" My feeling is that I should not change it, but that is a total guess on my part. Any...
15. ### COMSOL - Preventing a moving mesh from stretching in COMSOL simulation

Hello, I followed the following example for modeling the induced current from a moving magnet in a coil https://www.comsol.com/support/learning-center/article/Modeling-Induced-Currents-from-Moving-a-Magnet-Through-a-Coil-9871/112 If I have a bigger model with a bigger displacement of the...
16. ### Mesh hole size calculation for RFID signal blocking

For a project I am currently facing a problem that I find difficult to solve. I am developing a shielding portal that uses a mesh to blocks UHF RFID signals. I would like to use aluminium mesh due to it being lightweight and its attenuation properties. The frequency of UHF RFID signals in the...
17. ### How to use mesh tally in MCNPX to calculate dose?

Hello,guys, I wonder how to use mesh tally to calculate dose.I set a cylinder，and set the material of the cylinder.Then I want to divide a cylinder into smaller cylinders in a direction perpendicular to the z-axis.And I need to record the flux of each mesh,use dedf card to get dose. I have tried...
18. ### Engineering Mesh Analysis for time domains?

I've tried to solve the following circuit using mesh equation, but the solution seems to differ from my attempted answer. Mesh circuit as follows: My mesh equation is: -10+3(i1)+2s(i1-i2)=0 (for the mesh on the left) and -10+12(i2)+6s(i2)+2s(i2-i1)=0 (right mesh) However the answer seems to...
19. M

### Computational Fluid Dynamics and refining the mesh

Hi PF! I'm running a two-phase simulation, which takes a long time to run. The simulation is simply a partially filled tank being drained in zero gravity, and the tank is a little smaller than a mailbox (~ 160 X 40 X 40 mm). Before running the simulation I would like to know if my mesh is...
20. ### MCNP: mesh with weight window generator

Hallo everybody, I am using a mesh-based-weight window generator. It is clear to me that the coarse mesh must cover the full geometry; my doubt is about the fine mesh. Is it possible to define the fine mesh only in a part of a geometry, for example telling to MCNP to make 5 bins between y1 and...
21. ### Explaining Mesh Currents: Understanding the Relationship between i1 and i2

Here's my work. I have the correct answer, but I'd like to know why this only works for (i1-i2) plugged in for i_delta as opposed to what I initially put: i_delta = i2-i1. You can see this in the blue text above versus what I originally had in red.
22. ### Ridiculously low drag coefficient from OpenFOAM CFD

(New thread following up to a conversation in another thread). I'm using SimFlow 3.1 with OpenFOAM 5 on Linux to try to evaluate the drag coefficient of a water rocket body, constructed from a 2-liter Coke bottle with a conical nose, traveling through air at 77 m/s. This should be a simple...
23. ### Astrophysics question: Wire mesh radio telescope antenna

The answer says its 1 meter i don't understand how they arrived at this, The mark scheme suggests that the 50mm is the resolving power or Rayleigh criteria? https://downloads.umutech.net/Physics/Past_Papers/PA05/Astro/MS/physics_u5_astro_ms_jan_2003.pdf
24. ### Curious optical effect related to light passing through a mesh

I hope someone here can explain this curious light effect! Some background: I have a table with a laptop on it, and a chair sitting at this table that has a mesh back on it that has a pattern of ~2mm holes cut into black material in a regular pattern. I happened to notice one day that I could...
25. ### Mesh analysis of a circuit

Homework Statement Find the current in each resistor. (refer to uploaded diagram) Homework Equations ##Kirchhoff's Law: I_s=I_1 + I_2## Mesh analysis method The Attempt at a Solution I'm calling ##I_s## the total current before and after the current splitting up, and ##I_1## and ##I_2## are...
26. ### Engineering Circuit Mesh analysis question

Homework Statement Homework Equations I've worked out the KVL's for four meshes, I1, I2,I3, and I4. Would anyone be able to error check this for me? Also, would I be correct in thinking that I can use ohm's law by dividing V1/Z1 to find the current of the first mesh and likewise with...
27. ### 3d interpolation in Python using a mesh grid

I have four arrays of data xvalues[], yvalues[], zvalues[] and wvalues[] and I want to create, from this data, an interpolated function w = f(x,y,z). Is it easy to do this in python using first a meshgrid and then calling scipy's interpolation? e.g toy set up is something like, where wvalues...
28. ### Moving Mesh vs three phase field flow (Comsol)

I really don’t understand the advantage of 3 phase flow, phase field module in comsol. For example, if I want to simulate a compound droplet inside a fluid. Can’t I use the moving mesh with 2 fluid-fluid interface? If yes. When should I use the 3-phase flow, phase field simulation?
29. ### Energy dissipated in the resistors in a 2 mesh RC circuit

Homework Statement Hi mates, I have problems solving the third part of this exercise, I've already done all the previous calculations. Given the following circuit, where the switch S is open, the power supply = 50 volts and: The initial charge in the C capacitor: QC = 0 coulombs The initial...
30. ### How to find power and voltage using the mesh current method?

Hi. I am practising for my test and since I don't have the correct answers, I don't know if what I'm doing is right. I tried to solve this problem, can you check it and correct if it's wrong? Here's a clearer picture of the circuit. I suspect Uab isn't right, but am not sure. Thanks...
31. ### Mesh Analysis AC, solving simultaneous equations....

Homework Statement Hi guys I'm doing the mesh analysis of AC circuit and looking for some guidance. Here is the mesh picture and some components data: Homework Equations Kirchoff's voltage law and current law.The Attempt at a Solution I decided that mesh currents are going in clockwise...
32. ### Engineering Solve this Circuit using both Nodal Analysis and Mesh Analysis

Homework Statement [/B] Determine, Using the values given in TABLE A, the current I in the circuit of figure 2 by (a) Mesh analysis (b) Nodal analysis Circuit diagram and given variable attached. V1 = 120 V2 = j120 V3 = 14.142+j14.142 Z1= 2 Z2=-J5 Z3=4 Z4=-J5 Z5=J4Homework Equations [/B] KVL...
33. ### When using the Mesh Current Method -- How to handle current sources facing the wrong way

When using the Mesh Current Method and you encounter a loop with a current source that is going opposite to the mesh current do you write it down as a negative current source?
34. ### Node Analysis on Circuit: Solving for R3 Current

I have no idea how to do the node analysis for this circuit. I have done the mesh analysis and got the current in R3 to be 4A is this right?
35. ### Solving a circuit using both the mesh and node analysis

Homework Statement The problem asks to solve for i1, i2, and i3 using the mesh method in the following circuit: I will also include the link, because I noticed I am having trouble attaching the image to the post: https://imgur.com/a/bBvuLXM I would also like to confirm the answer by solving...
36. ### Open source adaptive mesh code

I want to start a project that requires parallel code for adaptive mesh refinement. I don't want to re-invent the wheel, and was hoping to leverage an open source library as a starting point. Does anyone have experience with any of these codes and could make a recommendation? At this point I...
37. ### Curved Mesh on Symmetry Boundary in ANSYS Maxwell 3D

I figured this would be the best place to ask as there doesn't seem to be a FEM/Simulation specific sub-forum here, but I am looking for some help regarding mesh generation in ANSYS Maxwell. I have an array of "micro-needles" that I am applying a voltage to in order to determine the electric...
38. ### Mesh Wi-Fi, extender, ADSL2+

I've recently moved into a house with ADSL2+. It is a very old old method of connecting to the internet. I'm having issues with the internet speeds as well as just generally connecting my devices. The biggest issue is that there is absolute no ethernet in the entire house. There is only one...
39. ### Completely stuck on mesh analysis

Homework Statement I have a circuit that I am to analyse and find I. I am told to use an excel matrix sheet given to me to solve 3 unknowns. I have 4 loops so this is a problem. I have made an attempt using three loops and referred to a previous thread on here for some help. It says I can do...
40. ### MCNPX Mesh Tally Problem: Offset of proton flux at surfaces

Dear all, we are using MCNPX for the simulation of proton beam interactions at our proton therapy facility. But now we found a very strange behavior within a RMESH1:h flux tally: In an even very simple geometry we see a constriction or rather offset of the Proton flux at surfaces (surface 1118...
41. ### Arbitrary current with mesh analysis

Given the circuit in the diagram I was wondering would I be able to make ib equal to the mesh i3. I have the equation for my Super Mesh at i1 and i3 which is: -25+30i3+5Va+20(i3-i2)+10(i1-i2)=0 (1). The mesh i2 is equal to -2A (2). subbing (2) into (1) gives: -25+50i3+5Va-30i2+10i1=0 (3)...
42. ### Mesh analysis -- Where does the negative sign come from?

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Hi, I couldn't figure out from the equation that relate the current source IS to IA and IB. If both IA and IB is coming from the same direction and the positive terminal has been predicted...
43. ### Sheet resistance of metal mesh

I would like to know the sheet resistance of a metal mesh that consists of 3 larger busbars (W=0.0025 cm L=0.3 cm) and 10 smaller fingers (W= 0.0002 cm L= 0,16416 cm) which are all connected by a big collection bar. The thickness of the whole layer is 0.00. This collection bar has been...
44. ### Engineering Writing mesh equations for a RL circuit

Homework Statement Write the equations for the two mesh current i1 and i2. The circuit and the answer to mesh 1 are showing below Homework EquationsThe Attempt at a Solution My answer came out to be the same as the answer key except for the -25di1/dt term. It seems that this term gets...
45. ### Frequency domain and mesh currents

Homework Statement Homework EquationsThe Attempt at a Solution So far I was able to transform each element into the frequency domain: I am just unsure how to work with the dots to find the mesh currents. Can someone explain? Thanks.
46. ### A Half-face traversal on general polyhedra

Hi, I'm developing a data structure to represent 3-D meshes for numeric simulation. I want those meshes to be able to handle any type of polyhedron (not only the classic tetra and hexahedron). The best data structure that I could find was one based on half-edges (or darts), such as this one...
47. ### Mesh analysis with dependent sources

Homework Statement I need to use mesh analysis to find the three currents: Homework EquationsThe Attempt at a Solution The answers are I1= -1.25A, I2=0.125A and I3 = 1.125A I don't know where I messed up for I3
48. ### How to do Mesh Analysis with current controlled voltage source

Homework Statement Vs = 100cos(2000t) Homework Equations KVL, KCL The Attempt at a Solution My mesh equations are: -Vs + I1(30-12.5j)-I2(120j)=0 4Ix+I2(120j+20)-I1(120j)=0 Ix = (I1-I2) Are these correct? When I solve I get a different result than when I do nodal analysis.
49. ### Mesh analysis with dependent voltage source

Homework Statement Find the: -Complex power delivered by source -Power factor of total load -Is the power factor leading, lagging, or in unity?[/B] Homework Equations KVL/KCL The Attempt at a Solution I want to solve this via mesh analysis to get currents. Mesh1: -10V + V1 + 0.75V1 = 0 V1 =...
50. ### Mesh Analysis w/ Supermesh and "different" current direction

Homework Statement Find power absorbed by resistor, capacitor and inductor. Find the total complex power absorbed by all the loads.[/B] Homework Equations KVL/KCL The Attempt at a Solution I want to solve this using Mesh analysis. There is a supermesh where the 5A source is, so I start it...