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Hello everyone,
I encountered a problem when I was trying to conducted axial piston pump simulation(just one piston) in fluent, the result of simulation shown in fluent is totally wrong, and I don’t know why, here is my train of thought.
Generally, I divided this simulation into two parts,
First part, slide mesh simulation for piston rotation around main axis. In this section, I deployed the MRF, frame motion, set rotation speed as 157.08 rad/s(1500rev/min), steady calculation;
Second part, dynamic mesh for piston axial movement. After the steady calculation was done, select the ‘Copy to mesh motion’, and change the time type into transient, run.

PS：I had also conducted the simulation in AMESim and Pumplinx, result from this two software agreed well.

Main settings:
1.mesh: mesh model includes two main parts, first, valve plate part which contain two parts, 1--- oil-in part, 2--- oil-out part; second, piston part which also include two parts, 1---piston cap, 2---piston cylinder.
(1) number of mesh: valve plate part, oil-in 19167 cells, oil-out 153169 cells; piston part, piston cap 14800 cells, piston cylinder 50853 cells;
(2) type of mesh: valve plate part--- Tera/Mixed; piston part---hex;
(3) refinement domain: valve plate---damper groove(triangular)

2. Model: (1) Mixture: all set are default;
Main phase, fluid-oil;
Second phase, vapor;
(2) Cavitation model: transition: fluid to vapor, vapor pressure 3540 Pascal;

3.Control Method:
(1) Steady simulation(rotation part): SIMPLE, other settings---all default;
(2) Transient simulation(dynamic mesh part): PISO, other settings---all default;

4.Criterion: all criterion are set as 10^(-5) in both steady and transient;

5.Transient settings:
(1) step size:0.0004,
(2) number of steps:310

6.Boundary condition:
(1) inlet: 0 pascal;
(2) outlet: 0 pascal.

7. UDF code is as follows:
#include<stdio.h>
#include "udf.h"
DEFINE_CG_MOTION(motion1, dt, cg_vel, cg_omega, time, dtime)
{
cg_vel[1] = 157.07963 * 0.04929 * 0.3639 * sin(157.07963 * time);
printf("vel=%d \n", cg_vel[1]);
}

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every single mesh part has been uploaded as follows.

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Settings in fluent are as follows.

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settings of monitor, and residuals, displacement, flow rate at outlet, pressure in piston.

besides, I found that in the residual figure, the residuals could not reach the expected criterion in the period that corresponded to the end of one revoluntion, why ?

[jha.kashyap]

impressive study! Have you got satisfactory results?

[SKD070809]

can we connect to discuss more on linkedIn, since I am also working on same problem.

[jha.kashyap]

Sure, my mail id is jha.kashyap@gmail.com. send me invitation