[lfla]

Hi Samcfd,

I am doing something similar i have applied the udf to the airfoil with a 20deg pitching amplitude and set the fluid as deforming but i keep getting negative volume detected and i have changed some of the settings but problem persists, did you eventually sort out the problem you were having?

[jinsong]

hi, dear cheaklapomme.
maby your udf work now? i want to do the same case of that,and i have the same code of you ,could you give me any guide.thanks a lot.

Originally Posted by cheaklapomme

Hi guys,

I'v read all your posts, I tried everything you've said, but (yes there is always a 'but') I always have the best answer in the world

'Update dynamic mesh failed. Negative cell volume detected'

My project is blood simulation in artery, and what I want to do now is a simulation of the movement of the artery.

First of all I'll try to do that with an easy one, that's mean with a pipe.
Here is my UDF :

# include "udf.h"
# include "dynamesh_tools.h"
# define D 0.2e-2 /* diameter of the pipe */
# define H 0.03e-2 /* amplitude of the wave */
# define L 1e-2 /* length of the wave */
# define l 2e-2 /* lenght of the pipe */
# define speed_wave 1 /* speed of the wave */
static real F(real x)
{
if (x>=0 && x<L)
{ return H*sin(2*M_PI/L*(x-0.25*L))+0.5*D+H; }
else if(x>=L && x<=(L+l))
{ return 0.5*D; }
else
{ Message0("x = %12.4e Wrong range of x-aborting", x);
exit(1); }
}

static real f_top(real x)
{
real x1;
double tmp;
x1 = modf(x/(L+l), &tmp);
if (x1>=0)
{
return F(x1*(L+l)); }
else
{
return F((1+x1)*(L+l)); }
}
static real f_bottom(real x)
{
return -f_top(x);
}

DEFINE_GRID_MOTION(grid_top, domain, dt, time, dtime)
{
face_t f;
Thread *tf = DT_THREAD ((Dynamic_Thread *)dt);
int n;
Node *v;
/* Activate the deforming flag on adjacent cell zone, which means that
the cell adjacent to the deforming wall will also be deformed in
order to avoid skewness. */
SET_DEFORMING_THREAD_FLAG (THREAD_T0(tf));

/* Loop over the deforming boundary zone's faces; inner loop loops over
all nodes of a given face; */
begin_f_loop(f, tf)
f_node_loop(f, tf, n)
{
v = F_NODE(f, tf, n);
{
/* Update the current node only if it has not been previously visited to
avoid to visit the same nodes multiple times */

if (NODE_POS_NEED_UPDATE(v))

{
/* Set flag to indicate that the current node's position has been
updated, so that it will not be updated during a future
pass through the loop */
NODE_POS_UPDATED(v);
real x;
x = NODE_X(v);
/* f_top(x-ct) defines the wave equation */
NODE_Y(v) = f_top(x-speed_wave*time);
}
}
Update_Face_Metrics (f, tf);
}
end_f_loop (f, tf);
}

/* Similar udf for the bottom wall */
DEFINE_GRID_MOTION(grid_bot, domain, dt,
time, dtime)
{
face_t f;
Thread *tf = DT_THREAD ((Dynamic_Thread
*)dt);
int n;
Node *v;
SET_DEFORMING_THREAD_FLAG
(THREAD_T0(tf));
begin_f_loop(f, tf)
{
f_node_loop(f, tf, n)
{

v = F_NODE(f, tf, n);
if (NODE_POS_NEED_UPDATE(v))
{
NODE_POS_UPDATED(v);
real x;
x = NODE_X(v);
NODE_Y(v) = f_bottom(x-speed_wave*time);
}
}
Update_Face_Metrics (f, tf);
}
end_f_loop (f, tf);

}

I'm waiting for your possibilities and advices.

Thanks a lot in advance.

Christophe

[mohkh]

Originally Posted by cheaklapomme

Hi guys,

I'v read all your posts, I tried everything you've said, but (yes there is always a 'but') I always have the best answer in the world

'Update dynamic mesh failed. Negative cell volume detected'

My project is blood simulation in artery, and what I want to do now is a simulation of the movement of the artery.

First of all I'll try to do that with an easy one, that's mean with a pipe.
Here is my UDF :

# include "udf.h"
# include "dynamesh_tools.h"
# define D 0.2e-2 /* diameter of the pipe */
# define H 0.03e-2 /* amplitude of the wave */
# define L 1e-2 /* length of the wave */
# define l 2e-2 /* lenght of the pipe */
# define speed_wave 1 /* speed of the wave */
static real F(real x)
{
if (x>=0 && x<L)
{ return H*sin(2*M_PI/L*(x-0.25*L))+0.5*D+H; }
else if(x>=L && x<=(L+l))
{ return 0.5*D; }
else
{ Message0("x = %12.4e Wrong range of x-aborting", x);
exit(1); }
}

static real f_top(real x)
{
real x1;
double tmp;
x1 = modf(x/(L+l), &tmp);
if (x1>=0)
{
return F(x1*(L+l)); }
else
{
return F((1+x1)*(L+l)); }
}
static real f_bottom(real x)
{
return -f_top(x);
}

DEFINE_GRID_MOTION(grid_top, domain, dt, time, dtime)
{
face_t f;
Thread *tf = DT_THREAD ((Dynamic_Thread *)dt);
int n;
Node *v;
/* Activate the deforming flag on adjacent cell zone, which means that
the cell adjacent to the deforming wall will also be deformed in
order to avoid skewness. */
SET_DEFORMING_THREAD_FLAG (THREAD_T0(tf));

/* Loop over the deforming boundary zone's faces; inner loop loops over
all nodes of a given face; */
begin_f_loop(f, tf)
f_node_loop(f, tf, n)
{
v = F_NODE(f, tf, n);
{
/* Update the current node only if it has not been previously visited to
avoid to visit the same nodes multiple times */

if (NODE_POS_NEED_UPDATE(v))

{
/* Set flag to indicate that the current node's position has been
updated, so that it will not be updated during a future
pass through the loop */
NODE_POS_UPDATED(v);
real x;
x = NODE_X(v);
/* f_top(x-ct) defines the wave equation */
NODE_Y(v) = f_top(x-speed_wave*time);
}
}
Update_Face_Metrics (f, tf);
}
end_f_loop (f, tf);
}

/* Similar udf for the bottom wall */
DEFINE_GRID_MOTION(grid_bot, domain, dt,
time, dtime)
{
face_t f;
Thread *tf = DT_THREAD ((Dynamic_Thread
*)dt);
int n;
Node *v;
SET_DEFORMING_THREAD_FLAG
(THREAD_T0(tf));
begin_f_loop(f, tf)
{
f_node_loop(f, tf, n)
{

v = F_NODE(f, tf, n);
if (NODE_POS_NEED_UPDATE(v))
{
NODE_POS_UPDATED(v);
real x;
x = NODE_X(v);
NODE_Y(v) = f_bottom(x-speed_wave*time);
}
}
Update_Face_Metrics (f, tf);
}
end_f_loop (f, tf);

}

I'm waiting for your possibilities and advices.

Thanks a lot in advance.

Christophe

Dear Sir
I am looking to find a solution to my problem. So I found your response to some student and I hope to help me.
I want to simulate an elbow artery by using dynamic mesh. I need to apply eq Ra(t)=0.4+20sin 7.89*t
That can apply it on the wall and it will expand and converge according to the eq..
Please could you help me to write the right code as a UDF?
Thank you very much

Note: I have attached some file refer to the geometry and derivatives eqs

Best regards

[Sittisak]

Originally Posted by arunraj

Hi everyone,

I am simulating flapping wing of aerofoil. I have created three zones, zone 1, 2 and 3. Zone 1 has aerofoil with structured mesh around the aerofoil. Zone 2 and 3 has unstructured gird. My problem is I have properly followed all the steps. But I am not able to achieve what I want. Because the shadow of the interface is taking as wall and is not moving along with the domain. Kindly someone help in sorting out this issue. I have attached my UDF alos. Please have a look. Thank you so much

https://drive.google.com/file/d/0B7L...ew?usp=sharing
https://drive.google.com/file/d/0B7L...ew?usp=sharing

I would like some advice about this problem I would like to use moving mesh or dynamic mesh with UDF for Morphing Airfoil I don't know how to use it. Please give me some advice. I'm student and leaning to this project I don't look your link on sharing would you please to sent to me at my E-mail? : agisan.r@gmail.com



Sittisak. Thank you very much.

[Sittisak]

I would like some advice about this problem I would like to use moving mesh or dynamic mesh with UDF for Morphing Airfoil I don't know how to use it. Please give me some advice. I'm student and leaning to this project I don't look your link on sharing would you please to sent to me at my E-mail? : agisan.r@gmail.com

Sittisak. Thank you very much.